The factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. 8! = 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1 equals 40,320.
Explanation:In Mathematics, the factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. For instance, 8! means multiplying together 8, 7, 6, 5, 4, 3, 2 and 1. So, the calculation would look like this: 8! = 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1 = 40,320. Therefore, the value of 8! is 40,320.
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Mickey works in a square shaped office. The area of his office is 110.25 ft2. What is the length of one side of Mickey’s office?
Answer: A formula that can be used to find the answer is (x Squared = 110.25) So (x times x = 110.25) 10.5 is the length of one side because 10.5 squared = 110.25.
Answer is 10.5
Final answer:
To find the length of one side of Mickey’s square-shaped office with an area of 110.25 square feet, we take the square root of the area, resulting in a side length of 10.5 feet.
Explanation:
The question asks for the length of one side of Mickey’s square-shaped office given that the area of the office is 110.25 square feet. To find the length of one side, we can use the formula for the area of a square, which is area = side², where ‘side’ represents the length of one side of the square. Given that the area = 110.25 ft², we solve for the side length by taking the square root of the area.
So, the calculation would be side = √(110.25 ft²), which equals 10.5 feet. Therefore, the length of one side of Mickey’s square office is 10.5 feet.
Slitsnails are large mollusks that live in deep waters. They have been found in the range of elevations shown. Write and graph an inequality that represents this range. 100ft - 2500ft
Answer:
The range could be written in inequality form will be [tex]-2500\leq x\leq -100[/tex].
Step-by-step explanation:
Slitsnails live in the deep water. It is given that they live between a depth of 100 ft to 2500 ft.
Let [tex]x[/tex] represents the depth of water from the water surface.
As we go down the water, the depth will be negative.
So, the depth could vary from 100 ft to 2500 ft.
The minimum depth should be 100 ft and the maximum depth is 2500 ft.
Thus, the range could be written in inequality form as,
[tex]-2500\leq x\leq -100[/tex]
In a graph, the inequality can be shown as,
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The inequality representing the range of elevations for Slitsnails is x ≥ 100 and x ≤ 2500. The graph of the inequality shows the range on a number line.
Explanation:Inequality representing the range of elevations for Slitsnails:The range of elevations for Slitsnails is from 100ft to 2500ft. To write an inequality, we'll use the variable x to represent the elevation. The inequality can be written as:
x ≥ 100 and x ≤ 2500
Graph of the inequality:To graph this inequality, we'll plot the values on a number line. We'll start at 100 and draw a closed circle to represent that the value is included in the range. Then, we'll draw an arrow to the right to show that the values continue up to 2500, but do not include 2500. The graph will look like:
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ILL GIVE BRAINLIEST PLEASE HELP MEEE
An elephant weighs 1.1 × pounds. A giraffe weighs 2.1 × pounds. How much more does the elephant weigh than the giraffe? A. 1.0 × pounds B. 8.9 × pounds C. 1.0 × pounds D. 8.9 × pounds
Answer:
8.9 x 10^3
:D
Step-by-step explanation:
Mrs.Cox is baking a ham for dinner. It takes 1 hour and 30 minutes to bake. The family eats at 6:15 p.m. What time should Mrs.Cox put the ham in the oven?
Solve 1/2 - 60% -25%
Answer:
-35%
Step-by-step explanation:
To solve this equation, the first thing we have to do is to convert percentages to decimals because we are doing mathematical operations with a fraction.
To convert a percentage to a decimal, we just divide by 100. So, 60% equals 0.60, and 25% equals 0.25.
Next, we subtract these values from 1/2.
So, we have the following steps:
1. Calculate 1/2 - 0.60 (which is the decimal equivalent of 60%). This gives us -0.10.
2. Then subtract 0.25 (which is the decimal equivalent of 25%) from the result. So, -0.10 - 0.25 equals -0.35.
Therefore, 1/2 - 60% - 25% equals -0.35.
Which of these is a simplified form of the equation 9y + 6 = 9 + 2y + 2y
9y = 7
5y = 3
13y = 15
4y = 15
9y + 6 = 9 + 2y + 2y
9y + 6 = 9 + (2y + 2y)
9y + 6 = 9 + 4y subtract 6 from both sides
9y = 3 + 4y subtract 4y from both sides
5y = 3Answer:
5y = 3
Step-by-step explanation:
9y + 6 = 9 + 2y + 2y
9y + 6 = 9 + (2y + 2y)
9y + 6 = 9 + 4y subtract 6 from both sides
9y = 3 + 4y subtract 4y from both sides
5y = 3
A battery is 10% charged and is charging at a constant rate. The graph shows the battery’s charge over time. What is the slope of the line that represents the situation? Enter the slope as a fraction.
Answer:
The slope of the line is 3/4
Step-by-step explanation:
There is a difference of 3 in the y coordinate and 4 for the x coordinate from each exact point.
How do you solve this?? A line has a slope of 2. It passes through the points (1, 2) and (3, y) . What is the value of y?
The formula of a slope:
[tex]m=\dfrac{y_2-y_1}{x_2-x_1}[/tex]
We have m = 2 and the points (1, 2) and (3, y). Substitute:
[tex]\dfrac{y-2}{3-1}=2\\\\\dfrac{y-2}{2}=2\qquad\text{multiply both sides by 2}\\\\y-2=4\qquad\text{add 2 to both sides}\\\\\boxed{y=6}[/tex]
What fraction is less than 1/2
Answer:
A. 3/8
Step-by-step explanation:
Step 1. Change the denominators so they are the same value
1/2 x 4 = 4/8
Step 2. Compare
3/8 < 4/8
Answer:
A. [tex]\dfrac{3}{8}[/tex] is smaller than [tex]\dfrac{1}{2}[/tex].
Step-by-step explanation:
The given fraction is [tex]\dfrac{1}{2}[/tex].
To compare two fractions, either numerator or denominator should be equal.
It is required to compare the given fraction with [tex]\dfrac{3}{8}[/tex] and [tex]\dfrac{5}{8}[/tex].
Now, the given fraction can be written as,
[tex]\dfrac{1}{2}\times\dfrac{4}{4}=\dfrac{4}{8}[/tex]
Now, the denominator of the given fraction is equal to that of other fractions.
In the fraction [tex]\dfrac{3}{8}[/tex] , numerator 3 is smaller than that of the given fraction which is 4.
So, the fraction [tex]\dfrac{3}{8}[/tex] is smaller than [tex]\dfrac{1}{2}[/tex].
In the fraction [tex]\dfrac{5}{8}[/tex] , numerator 4 is larger than that of the given fraction which is 4.
So, the fraction [tex]\dfrac{5}{8}[/tex] is larger than [tex]\dfrac{1}{2}[/tex].
Therefore, A. [tex]\dfrac{3}{8}[/tex] is smaller than [tex]\dfrac{1}{2}[/tex].
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Which television as more viewing area: the 42 inch 16:9 television or the 32 inch 4:3?
Answer: 42 inch 16:9 television
Step-by-step explanation:
The dimensions of 42 inch 16:9 television are:
Width of the television = 36.6 inches
Height of the television = 20.6 inches
Screen Area of the television = 36.6 x 20.6 = 753.96 sq inches
The dimensions of 32 inch 4:3 television are:
Width of the television = 25.6 nches
Height of the television = 19.2 inches
Screen Area of the television = 25.6 x 19.2 = 491.52 sq inches
Thus 42 inches 16:9 television has 262.44 square inches more screen area.
Hope it helps.
Thanks you :)
[tex]\text{Look at the picture.}[/tex]
[tex]x, y - some\ units\ of\ leng th[/tex]
[tex]\text{Use the Pythagorean theorem:}[/tex]
[tex](16x)^2+(9x)^2=42^2\\\\256x^2+81x^2=1764\\\\337x^2=1764\qquad\text{divide both sides by 337}\\\\x^2=\dfrac{1764}{337}\to x=\sqrt{\dfrac{1764}{337}}[/tex]
[tex]\text{The area:}\\\\A_1=16\sqrt{\dfrac{1764}{337}}\cdot9\sqrt{\dfrac{1764}{337}}=(16)(9)\left(\sqrt{\dfrac{1764}{337}}\right)^2\\\\=144\cdot\dfrac{1764}{337}\approx754\ in^2[/tex]
[tex](4x)^2+(3x)^2=32^2\\\\16x^2+9x^2=1024\\\\25x^2=1024\qquad\text{divide both sides by 25}\\\\x^2=40.96\to x=\sqrt{40.96}\to x=6.4\ in\\\\\text{The area:}\\\\A_2=4(6.4)\cdot3(6.4)=25.6\cdot19.2=491.52\ in^2[/tex]
[tex]754 > 491.52[/tex]
[tex]\text{Answer: 42 in 16 : 9.}[/tex]buddy has 1 out of 11 students in the classroom who are spreading christmas cheer. what % of the class is he?
Answer:
9%
Step-by-step explanation:
1/11 students
1 divided by 11
=0.09090909090909
to convert the decimal to a percentage, multiply 100 to .09
9%
What is the measure of arc ab
34
70
110
104
Answer: choice B) 70 degrees
Minor arc AB is equal in measure to the central angle BPA, which cuts off the arc in question.
Easy 7 points!!! Please help!! Consider the function f(x)=-2/3x+5 what is f(-1/2)? Enter your answer as a simplified fraction in the box. F(-1/2)=
Answer:
F(-1/2)= 5 1/3
Step-by-step explanation:
-1/2 X -2/3 = 1/3 because the two negatives cancle out. 1/3 + 5=
5 and 1/3.
Answer:
5 1/3
Step-by-step explanation:
What is the justification for each step in the solution of the equation?
Given
Step 1: They multiplied 3 on both sides of the equation to get rid of the denominator (you can do this because the denominators were the same number, which was 3)
Step 2: They distributed 6 into (x + 2)
Step 3: They added 1 on both sides
Step 4: They subtracted 6x on both sides to get "x" on one side of the equation
Step 5: They divided -4 on both sides to get "x" by itself
If it takes 15.25(432g) of flour to make 24 cupcakes how much flour will it take to make 6 cupcakes?
6 cupcakes is 1/4 of 24 ( 24 / 6 = 4).
This means you would need 1/4 the amount of flour.
Divide the amount needed for 24 cups by 4:
15.25 / 4 = 3.8125
Round answer as needed.
Answer:
3.8125 (108g) of flour are required
Step-by-step explanation:
We can use ratio's to solve this problem
432 g x g
------------ = -----------
24 cupcakes 6 cupcakes
Using cross products
432*6 = 24x
Divide each side by 24
432*6/24 = 24x/24
108 =x
108 grams
If we needed to use 15.25 units? instead
15.25 x
------------ = -----------
24 cupcakes 6 cupcakes
15.25 * 6 = 24x
Dividing by 24 on each side
15.25 *6/24 = 24x/24
3.8125 =x
Which function is undefined for x = 0? y=3√x-2 y=√x-2 y=3√x+2 y=√x=2
For this case, we must indicate which of the given functions is not defined for[tex]x = 0[/tex]
By definition, we know that:
[tex]f (x) = \sqrt {x}[/tex] has a domain from 0 to infinity.
Adding or removing numbers to the variable within the root implies a translation of the function vertically or horizontally. For it to be defined, the term within the root must be positive.
Thus, we observe that:
[tex]y = \sqrt {x-2}[/tex] is not defined, the term inside the root is negative when [tex]x = 0[/tex].
While [tex]y = \sqrt {x + 2}[/tex] if it is defined for [tex]x = 0.[/tex]
[tex]f(x)=\sqrt[3]{x}[/tex], your domain is given by all real numbers.
Adding or removing numbers to the variable within the root implies a translation of the function vertically or horizontally. In the same way, its domain will be given by the real numbers, independently of the sign of the term inside the root.
So, we have:
[tex]y = \sqrt [3] {x-2}[/tex] with x = 0: [tex]y = \sqrt [3] {- 2}[/tex] is defined.
[tex]y = \sqrt [3] {x + 2}[/tex]with x = 0: [tex]y = \sqrt [3] {2}[/tex]in the same way is defined.
Answer:
[tex]y = \sqrt {x-2}[/tex]
Option b
The function that are undefined for (x=0) is [tex]y = \sqrt[3]{x-2}[/tex] and [tex]y = \sqrt{x-2}[/tex] and this can be determined by putting (x=0) in all the given expressions.
Given :
Function 1 - [tex]y = \sqrt[3]{x-2}[/tex]
Function 2 - [tex]y = \sqrt{x-2}[/tex]
Function 3 - [tex]y = \sqrt[3]{x+2}[/tex]
Function 4 - [tex]y = \sqrt{x+2}[/tex]
Evaluate each function at (x = 0) to determine which function is undefined for (x = 0).
Function 1 - [tex]y = \sqrt[3]{x-2}[/tex]
put (x = 0) in above function:
[tex]y = \sqrt[3]{-2}[/tex]
Therefore, it can be concluded that the above function is not defined for (x=0).
Function 2 - [tex]y = \sqrt{x-2}[/tex]
put (x = 0) in above function:
[tex]y = \sqrt{-2}[/tex]
Therefore, it can be concluded that the above function is not defined for (x=0).
Function 3 - [tex]y = \sqrt[3]{x+2}[/tex]
put (x = 0) in above function:
[tex]y = \sqrt[3]{2}[/tex]
Therefore, it can be concluded that the above function is defined for (x=0).
Function 4 - [tex]y = \sqrt{x+2}[/tex]
put (x = 0) in above function:
[tex]y = \sqrt{2}[/tex]
Therefore, it can be concluded that the above function is defined for (x=0).
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Write an explicit formula for the recursive formula shown below: A(n)=A(n-1)+3; A(1)=6
Answer:
[tex]a_n=A(n)=3n+3.[/tex]
Step-by-step explanation:
You are given recursive formula [tex]A(n)=A(n-1)+3,[/tex] where [tex]A(1)=6.[/tex]
Find some terms of the sequence:
[tex]a_1=A(1)=6,\\ \\a_2=A(2)=A(1)+3=6+3=9,\\ \\a_3=A(3)=A(2)+3=9+3=12,\\ \\a_4=A(4)=A(3)+3=12+3=15,...[/tex]
You van see that these terms form the arithmetic sequence with first term [tex]a_1=6[/tex] and difference [tex]d=3.[/tex]
An explicit formula for n-th term of arithmetic sequence is
[tex]a_n=a_1+(n-1)d.[/tex]
In your case,
[tex]a_n=6+(n-1)\cdot 3,\\ \\a_n=6+3n-3,\\ \\a_n=3n+3.[/tex]
stefanie bought a pack of pencils for 1.75 and some erasers that cost 0.25 each, she paid a total of 4.25 for these items. how many erasers did she buy
Subtract the cost of the pencils from the total cost. This will be he amount she spent on erasers. Then divide that amount by the cost of each eraser to get the total.
4.25 - 1.75 = 2.50 spent on erasers
2.50 / 0.25 = 10
She bought 10 erasers.
Please help and show work!! I really need help please!!
[tex]\text{Let}\ k:y=m_1x+b_1\ \text{and}\ l:y=m_2x+b_2,\ \text{then}\\\\l\ \perp\ k\iff m_1m_2=-1\to m_2=-\dfrac{1}{m_1}\\-------------------------\\\\\text{We have}\ 5x+3y=8\qquad\text{subtract 5x from both sides}\\\\3y=-5x+8\qquad\text{divide both sides by 3}\\\\y=-\dfrac{5}{3}x+\dfrac{8}{3}\to m_1=-\dfrac{5}{3}\\\\\text{Therefore}\ m_2=-\dfrac{1}{-\frac{5}{3}}=\dfrac{3}{5}\\\\Answer:\ \boxed{b.\ \dfrac{3}{5}}[/tex]
--------------------------------------------------------
[tex]\text{Let}\ k:y=m_1x+b_1\ \text{and}\ l:y=m_2x+b_2,\ \text{then}\\\\l\ \parallel\ k\iff m_1=m_2\\\\\text{We have}\ 3x-5y=10\qquad\text{subtract 3x from both sides}\\\\-5y=-3x+10\qquad\text{divide both sides by (-5)}\\\\y=\dfrac{3}{5}x-2\to m_1=\dfrac{3}{5}\\\\\text{Therefore we have}\ m_2=\dfrac{3}{5}.\\\\Answer:\ \boxed{D.\ y=\dfrac{3}{5}x}[/tex]
Answer:
Answer Left Panel: 3/5 or B
Answer Right Panel: D
Step-by-step explanation:
Left Panel
5x + 3y = 8 Subtract 5x from both sides5x - 5x + 3y = - 5x + 8 Combine3y = - 5x+ 8 Divide by 33y/3 = -5x/3 + 8/3 y = - 5x/3 + 8/3 The slope of any line is the number with the x Slope of this line = -5/3The slope of two lines that are perpendicular when multiplied = - 1slope of the given line(m1) * slope of the perpendicular(m2) = - 1m1 * m2 = - 1-5/3 * m2 = - 1 Multiply by 3-5x/3 *3 = - 1 * 3 -5x = - 3 Divide by -5-5x/-5 = -3 / 5x = 3/5Right Panel
The slope of a line parallel to another line is the same as the given line.
The given line is 3x - 5y = 10 Subtract 3x from both sides3x - 3x - 5y = -3x + 10 Combine-5y = -3x + 10 Divide by - 5-5y/-5 = -3x/-5 + 10/-5 Do the divisiony = 3x/5 - 2 So look for a line with a slope of 3/5y= 3x /5 Answer DRound 0.996 to the nearest tenth
Answer:
1.0
Step-by-step explanation:
The answer is 1.0 It is not a tenth but 99 is closer to 100. witch is 1.0 Do you try looking it up. This is a site i used. It is great. It is called calculator soup.
choose as many that apply:
A progression is: any list of numbers, an arrangement of quantities whose positions are based upon the natural numbers, a summation of quantities based upon a sequence, new discoveries in mathematics.
Answer:
a progression is a summation of quantities based upon a sequence.
Step-by-step explanation:
example of a progression
1,4,7,10,13,16,.........
a1=1
a2=4
a3=7
difference =d=a2-aq=4-1=3
similarly
d=a3-a2=7-4=3
we can clearly see that there is a difference of 3 between two consecutive terms of a progression
on the other hand successive terms of a progression can be obtained by adding a unique value in backward term to get successive term.
hence a progression is a summation of quantities based upon a sequence
Answer:
A summation of quantities based upon a sequence, and an arrangement of quantities whose positions are based upon the natural numbers
Step-by-step explanation:
It cannot be "Any list of numbers" because a progression only contains natural numbers, meaning no decimals or fractions. It is also not a new discovery in mathematics.
Is -0.397 bigger than -2/6
Answer:
nooooooooooooooooooo
Step-by-step explanation:
if you divide -2 by 6, you get -0.3333333333... and since their negative -2/6 is a bigger number because -0.397 goes more left on the x axis.
Solve for x -6x +11< -9x+2
-6x + 11 < -9x + 2
Add 9x to both sides.
3x + 11 < 2
Subtract 11 from both sides.
3x < -9
Divide both sides by 3.
x < -3
The value of x is less than -3.Answer:
A
Step-by-step explanation:
If an object is dropped from a height of 55 feet, the function d = -16^2 + 55 gives the height of the object after t seconds. Graph this function. Approximately how long does it take the object to reach the ground (d=0)
Answer:
Approximately 1.9 seconds (correct to nearest tenth)
Step-by-step explanation:
Looks like the function is d = -16t^2 + 55 ( you left out the t)
The answer is the value of t when d = 0 so we have the equation:-
0 = -16t^2 + 55
16t^2 = 55
t^2 = 55/16
t = sqrt (55/16)
= 1.85 seconds
Answer:
t is approximately 1.854049622 seconds
Step-by-step explanation:
d = -16 t^2 + 55
Let d = 0
0 = -16 t^2 + 55
Subtract 55 from each side
-55 = -16 t^2
Divide by -16 on each side
-55/-16 = -16 /-16t^2
55/16 = t^2
Take the square root of each side
sqrt(55/16) = sqrt(t^2)
We only take the positive square root because time must be positive
sqrt(55/16) = t
t is approximately 1.854049622 seconds
the length of a rectangle is 4 less than twice the width. the perimeter of the rectangle is 34 feet. find the length and width of the rectangle.
Answer: The length is 10ft, the width is 7ft.
Step-by-step explanation:
Let L be the length
Let w be the width
The equation for the perimeter is:
2L+2w=34
We also know that L=2w-4
So we can insert L=2w-4 into 2L+2w=34
2(2w-4)+2w=34
4w-8+2w=34
6w=42
w=7
If the width is 7, we can insert it into 2L+2w=34 to find out the length
2L+14=34
2L=20
L=10
The width is 7 ft, the length is 10 ft.
The length and width of the rectangle are 10 feet and 7 feet respectively. This is determined by setting up and solving equations based on the given information about the relationship between the length and width and the perimeter of the rectangle.
Explanation:Given that the length (L) of the rectangle is 4 less than twice the width (W), we can represent this as:
L = 2W - 4
. We also know that the perimeter (P) of the rectangle is 34 feet. The formula for the perimeter of a rectangle is
P = 2L + 2W
. Substituting L in the perimeter equation gives
P = 2(2W - 4) + 2W = 34
. Simplifying the equation leads to
4W - 8 + 2W = 34
, and then
6W = 42
when you add 8 to both sides. Solving for W gives
W = 7 feet
. Substituting W = 7 into the length equation gives
L = 2(7) - 4 = 10 feet
. Therefore, the width and length of the rectangle are 7 feet and 10 feet respectively.
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What is the slope of the graph of the line,5x-7y=-30 PLEASE EXPLAIN
The -30 does not matter in this case because it does not affect the slope. So, you can ignore it and simplify the question to 5x-7y=0.
Move the -7y to the right to get 5x=7y. Then, divide by 7 to isolate y to get y=5x/7.
Therefore, the slope is 5/7.
Final answer:
The slope of the graph of the line 5x - 7y = -30 is 5/7, determined by rewriting the equation in the slope-intercept form and identifying the coefficient of the x term as the slope.
Explanation:
To find the slope of the graph of the line given by the equation 5x - 7y = -30, we need to rewrite the equation in the slope-intercept form, which is y = mx + b, where m is the slope, and b is the y-intercept. Starting with the given equation:
5x - 7y = -30
-7y = -5x - 30
y = (5/7)x + 30/7
From the transformed equation y = (5/7)x + 30/7, we can see that the slope (m) is 5/7. This means that for every one-unit increase in the independent (x) variable, the dependent (y) variable increases by 5/7 units.
Find the slope of the line containing the pair of points (9,2) and (-7,-9)
Answer:
-11/-16
Step-by-step explanation:
M= Y2 - Y1/ X2 - X1 = -9-(2)/ -7-(9) = -11/ -16
The slope of the line is 11/16.
How to find the slope of a straight line fro given coordinate points -The slope of any given formula can be found as
Slope = (y2 - y1)/(x2 - x1)
Where, y2 and y1 are the y-coordinates of the given two points
and, x2 and x1 are the x-coordinates of the given two points.
By the problem, y2 = -9 , y1 = 2 , x2 = -7 and x1 = 9
Using the above identity,
Slope = (-9 - 2) / (-7 - 9)
∴ Slope = -11 / -16 = 11/16 = 0.6875
Thus the slope of the line containing given points is 11/16
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The tank on Mr. Ramiras’ car holds 15 gallons of gasoline. If he gets 28.5 miles per gallon, how far can he travel on a full tank of gas?
Answer:
distance = 427.5 miles
Step-by-step explanation:
We can determine the distance by multiplying the miles per gallon by the number of gallons.
distance = mpg * gallons
distance = 28.5 mpg * 15 gallons
distance = 427.5 miles
Answer:
427.5 miles of gas
Step-by-step explanation:
This problem will require using multiplication to determine the distance in total.
We can multiply amount of gas car can hold times the miles per gallon to find the total distance.
Create an equation.
amount of gas car can hold * miles per gallon = distance
Solve by inputting numbers.
15 * 28.5 = 427.5
evaluate the expression. 1/2 - 4 (1/2 + 1)^2
A.-9
B. 9/4
C. 17/2
D. -17/2
Answer:
D. -17/2
Step-by-step explanation:
1/2 - 4 (1/2 + 1)^2
First we evaluate what is inside the parentheses
1/2 - 4 (3/2) ^2
Now we square what is inside the parentheses
1/2 - 4(9/4)
Now multiply
1/2 -9
Get a common denominator 9 = 9 *2/2 = 18/2
1/2 - 18/2
-17/2
Use PEMDAS:
P Parentheses first
E Exponents (ie Powers and Square Roots, etc.)
MD Multiplication and Division (left-to-right)
AS Addition and Subtraction (left-to-right)
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[tex]\dfrac{1}{2}-4\left(\dfrac{1}{2}+1\right)^2=\dfrac{1}{2}-4\left(1\dfrac{1}{2}\right)^2=\dfrac{1}{2}-4\left(\dfrac{1\cdot2+1}{2}\right)^2\\\\=\dfrac{1}{2}-4\left(\dfrac{3}{2}\right)^2=\dfrac{1}{2}-4\cdot\dfrac{3^2}{2^2}=\dfrac{1}{2}-4\cdot\dfrac{9}{4}=\dfrac{1}{2}-1\cdot\dfrac{9}{1}\\\\=\dfrac{1}{2}-9=\boxed{-8\dfrac{1}{2}=-\dfrac{8\cdot2+1}{2}=\boxed{-\dfrac{17}{2}}}\to\boxed{D.}[/tex]
At first, the ratio of Dave's savings to Sam's savings was 5:4. After each of them donated $40 to charity, the ratio of Dave's savings to Sam's savings became 13:10. What was Dave's savings at first?
Answer:
$300
Step-by-step explanation:
Let Dave's saving be D and Sam's savings be S
"At first, the ratio of Dave's savings to Sam's savings was 5:4":[tex]\frac{D}{S}=\frac{5}{4}\\4D=5S\\\frac{4}{5}D=S[/tex]
"After each of them donated $40 to charity, the ratio of Dave's savings to Sam's savings became 13:10":So we subtract 40 from each of them and then the ratio becomes 13 is to 10. Hence we can write:
[tex]\frac{D-40}{S-40}=\frac{13}{10}\\10(D-40)=13(S-40)\\10D-400=13S-520\\-400+520=13S-10D\\120=13S-10D[/tex]
Plugging in [tex]\frac{4}{5}D[/tex] into S (as we found earlier), we can solve for D (our answer):
[tex]120=13S-10D\\120=13(\frac{4}{5}D)-10D\\120=\frac{52}{5}D-10D\\120=\frac{2}{5}D\\D=\frac{120}{\frac{2}{5}}=120*\frac{5}{2}=300[/tex]
So, Dave's savings at first, D, is $300.