The integer n3 + 2n is divisible by 3 for every positive integer n

prove it by math induction

is it my proof right ?

Answers

Answer 1
P(n) = n^3 + 2n is divisible by 3 for every positive integer n.
Let's show that P(n) holds for n = 1
P(1) = 1^3 + 2(1) = 1 + 2 = 3 which is divisible by 3.

Now assuming, that p(k) is true, let's show that p(k + 1) is also true
p(k + 1) = (k + 1)^3 + 2(k + 1) = k^3 + 3k^2 + 3k + 1 + 2k + 2 = k^3 + 3k^2 + 5k + 3 = k^3 + 2k + 3k^2 + 3k + 3 = k^3 + 2k + 3(k^2 + k + 1), since P(k) is true => k^3 + 2k is true and 3(k^2 + k + 1) is divisible by 3 for all values of k wich shows that P(k + 1)is also true.
Therefore, P(n) is true for all positive integer value of n.
Answer 2

By the principle of mathematical induction, we have shown that for all positive integers n, n^3 + 2n is divisible by 3.

Proof by Induction: n^3 + 2n is divisible by 3 for all positive integers n.

Base Case:

For n = 1, n^3 + 2n = 1^3 + 2(1) = 3, which is divisible by 3.

Induction Hypothesis:

Assume that for some positive integer k, k^3 + 2k is divisible by 3. We can write this as: k^3 + 2k = 3m, where m is an integer.

Induction Step:

We need to show that (k + 1)^3 + 2(k + 1) is divisible by 3. Expanding the expression:

(k + 1)^3 + 2(k + 1) = k^3 + 3k^2 + 3k + 1 + 2k + 2

= (k^3 + 2k) + (3k^2 + 3k + 3)

Substituting the induction hypothesis:

= 3m + 3(k^2 + k + 1)

= 3(m + k^2 + k + 1)

Since k^2 + k + 1 is an integer (sum of three integers), and m is an integer, their sum (m + k^2 + k + 1) is also an integer. Therefore, (k + 1)^3 + 2(k + 1) is divisible by 3.


Related Questions

What is the r value of the following geometric sequence? 4, 7, 12.25, 21.4375.

Answers

to find the common ratio (r) divide the second term by the first term
7 / 4 = 1.75 <==

Answer:

r ( common ratio) = 1.75

Step-by-step explanation:

Given : geometric sequence 4, 7, 12.25, 21.4375.

To find : What is the r value .

Solution : We have given

Geometric sequence 4, 7, 12.25, 21.4375.

r ( common ratio) = [tex]\frac{second\ term}{first\ term}[/tex].

r ( common ratio) = [tex]\frac{7}{4}[/tex] = 1.75

r ( common ratio) = [tex]\frac{12.25}{7}[/tex] = 1.75

Therefore, r ( common ratio) = 1.75

CD is perpendicular to AB and passes through point C (5,12).

If the coordinates of A and B are (-10, -3) and (7, 14), respectively, the x- intercept of CD is:

(12, 0)
(15, 0)
(17, 0)
or (19,0).

The point:

(-5, 24)
(-2, 19)
(7, -10)
or (8, 11)

lies on CD.

Answers

The slope of AB is
[tex]m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}[/tex]
[tex]=\frac{14-(-3)}{7-(-10)}[/tex]
[tex]=\frac{17}{17}[/tex]
[tex]=1[/tex]

So the slope of CD is
[tex]-\frac{1}{m}=-\frac{1}{1}=-1[/tex]

The equation for CD is then
[tex]y=-x+b[/tex]
We find [tex]b[/tex] by plugging in the point [tex](5, 12)[/tex]:
[tex]12=-5+b[/tex]
[tex]\rightarrow b=17[/tex]
[tex]\rightarrow y=-x+17[/tex]

The x-intercept is found by setting [tex]y[/tex] equal to 0:
[tex]0=-x+17[/tex]
[tex]\rightarrow x=17[/tex]
which gives [tex](17, 0)[/tex].

For the second part, we just plug in the different points and see if the equation is true:
[tex](-5, 24)\rightarrow 24=-(-5)+17\rightarrow 24=5+17\rightarrow 24=22[/tex]
(doesn't work)
[tex](-2, 19)\rightarrow 19=-(-2)+17\rightarrow 19=2+17\rightarrow 19=19[/tex]
So the answer must be [tex](-2, 19)[/tex].

Answer

CD is 17,0

The point -2,19

Step-by-step explanation:

solve this problem 2-(-8)+(-3)=

Answers

Answer:

7

Step-by-step explanation:

(-)(-) = (+)

(-)(+) = (+)(-) = (-)

(+)(+) = (+)

2 - (-8) + (-3) = (*)

-(-8) = 8

+(-3) = -3

(*) = 2 + 8 - 3 = 10 - 3 = 7

In rectangle ABCD, BC=30 and AB=40. If diagonals AC and BD intersect at E, find the measure of BE.

Answers

Final answer:

To find the measure of BE in rectangle ABCD, we can use the properties of a rectangle and similar triangles. By using the Pythagorean theorem, we find the length of the diagonal AC. Then, we use the properties of similar triangles to calculate the length of BE.

Explanation:

To find the measure of BE, we can use the properties of a rectangle. In rectangle ABCD, the diagonals are equal in length and bisect each other. Therefore, we can use the Pythagorean theorem to find the length of the diagonal AC: AC^2 = AB^2 + BC^2. Plugging in the values given, AC^2 = 40^2 + 30^2 = 2500, so AC = sqrt(2500) = 50. Since the diagonals bisect each other, we can conclude that AE = 50/2 = 25. Now, we can use the properties of similar triangles to find the length of BE. Triangle ABE is similar to triangle ACE, so we can set up the following proportion: AB/AC = BE/AE. Plugging in the values, 40/50 = BE/25. Solving for BE, we get BE = (40/50) * 25 = 20.

Final answer:

To find the measure of BE in rectangle ABCD, we use the Pythagorean Theorem. As the diagonals bisect each other, BE is half the length of diagonal AC, resulting in BE = 25.

Explanation:

In rectangle ABCD with BC=30 and AB=40, the diagonals bisect each other. That means E, the point of intersection, is the midpoint of both diagonals AC and BD. Since ABCD is a rectangle, its diagonals are equal, and AC = BD. To find BD, we use the Pythagorean Theorem in ΔABC:

AC² = AB² + BC²AC² = 40² + 30²AC² = 1600 + 900AC² = 2500AC = √2500AC = 50

Since E is the midpoint of BD, BE is half the length of BD:

BE = BD/2BE = AC/2 (because AC = BD)BE = 50/2BE = 25

Varia is studying abroad in Europe. She is required to pay $3500USD per year to the university, however she must pay in euros. How many euros can Varia expect to pay per month to the university? (Round to the nearest whole euro.)

0.7306 euros = 1 US dollar

Answers

The answer would be 274.46 euros a month.

A bird flies from the bottom of a canyon that is 59 and three fifths

feet below sea level to a nest that is 609 and one fifth

feet above sea level. What is the difference in elevation between the bottom of the canyon and the​ bird's nest?

Answers

the difference in elevation between the bottom of the canyon and the nest is 668 and four fifths feet

solve x ​2 ​​ −18x+81=0 for x

Answers

I hope this helps you

The triangular region shows the number of possible raisins, x, and number of possible chocolate chips, y, a baker can use in a recipe.

Which combination of raisins and chocolate chips can the baker use?

A. 28 raisins and 20 chocolate chips
B. 33 raisins and 25 chocolate chips
C. 45 raisins and 10 chocolate chips
D. 55 raisins and 12 chocolate chips

Answers

Based on the given figure above, the correct answer would be option A. Given the triangular region that shows the number of possible raisins, x, and number of possible chocolate chips, y, a baker can use in a recipe, the combination of raisins and chocolate chips that the baker can use would be 28 raisins and 20 chocolate chips. Hope this answer helps.

we will proceed to verify each of the cases to determine the solution of the problem

we know that

The combination of raisins and chocolate chips that can the baker use, must be inside the triangular region

so

we're graphing each of the cases

Let

x--------> the number of possible raisins

y--------> the number of possible chocolate chips

case A

Let

[tex]A(28,20)[/tex]

using a graphing tool

see the attached figure

The point [tex]A(28,20)[/tex] is  include inside the triangular region

therefore

The case A is a solution

case B

Let

[tex]B(33,25)[/tex]  

using a graphing tool

see the attached figure

The point [tex]B(33,25)[/tex] is not include inside the triangular region

therefore

The case B is not a solution

case C

Let

[tex]C(45,10)[/tex]  

using a graphing tool

see the attached figure

The point [tex]C(45,10)[/tex] is not include inside the triangular region

therefore

The case C is not a solution

case D

Let

[tex]D(55,12)[/tex]    

using a graphing tool

see the attached figure

The point [tex]D(55,12)[/tex] is not include inside the triangular region

therefore

The case D is not a solution

the answer is the option A

[tex](28,20)[/tex]


A. 3x^2+2x-7
B. 3x^2+2x-3
C. 3x^2+8x+3
D. 5x^2+8x-7

Answers

I hope this helps you
answer is A. 3x^2+2x-7

4x^2+5x-2 - (x^2+3x+5)
=4x^2+5x-2 - x^2 - 3x - 5
=3x^2+2x-7

Write a linear equation in slope intercept form to model a tree 4 feet tall the grows 3 inches per year

Answers

y = 3x + 48  where x is your number of years. I got 48 by multiplying 4 and 12 since there are 12 inches in a foot. (:
Final answer:

The linear equation that models the growth of a tree that is 4 feet tall and grows 3 inches per year is y = 3x + 48.

Explanation:

The problem involves writing a linear equation in slope-intercept form to model the growth of a tree. The slope-intercept form is given by the equation y = mx + b, where 'm' represents the slope or the rate of change, and 'b' is the y-intercept or the initial value.

In the context of this problem, the tree's initial height is 4 feet and it grows at a rate of 3 inches per year. However, the units of the initial height and the yearly growth rate are different, so we need to convert 4 feet into inches. As 1 foot is equivalent to 12 inches, the initial height of the tree is 4 * 12 = 48 inches.

Therefore, the slope or rate of change 'm' is 3 inches per year and the y-intercept or initial value 'b' is 48 inches. Substituting these values into y = mx + b gives us the linear equation representing the growth of the tree: y = 3x + 48.

Learn more about Linear Equations here:

https://brainly.com/question/32634451

#SPJ3

Selina claims single having one exemption. Her state tax deduction is 21% of her federal tax contribution. Calculate the amount of state tax Selina owes if her gross pay for two weeks is $840. The following federal tax table is for biweekly earnings of a single person.

Answers

Answer:  

$16.80

Step-by-step explanation:

All real numbers that are greater than or equal to -1.5 and less than 9.2

Answers

So in order to answer this, let us put x as the real numbers. So based on the given values above, we can represent x this way:  −1.5 ≤x <9.2
Negative 1.5 is less than or equal to x and 9.2 is greater than or equal to x. Hope this is the answer that you are looking for. 

A real estate agent sells a house for $92,000. She receives a 6% commission on the sale of the house. How much did she earn on the sale? Round your answer to the nearest cent. Enter your answer in the box. $

Answers

It's literally just 92,000x.06

$5,520.00

The area of a square is found by squaring one of its sides, (A = s 2). A certain square has an area of z 2 + 18z + 81. Factor the trinomial to find a side of the square.

A.) side = z + 27
B.) side = z + 18
C.) side = z + 9

Answers

the answer is c =z+9

Answer:

C.) side = z + 9

Find P(Not a 2).
X 1 2 3 4
P(X) 0.30 0.40 0.15 0.15
A. 0.70
B. 0.60
C. 0.30
D. 0.40

Answers

B. 0.60

derp derp derp

Answer:

Option B is correct.    

Step-by-step explanation:

We have been given the different probabilities at different point we need to find the probability of not of 2

We know that sum of probabilities is 1

[tex]P(a_2)+P(not a_2)=1[/tex]

Here, the probability that is P(a 2)=0.40

Hence, the required probability is 1-0.40=0.60

Therefore, option B is correct.

What are the sine, cosine, and tangent of Θ = 3 pi over 4 radians?

Answers

Our angle teta is:
teta = 3pi/4

since that is larger than pi/2 but less than pi that means that our angle lies in II quadrant (x negative y positive)

sin(3pi/4) = √2/2
cosine and tangent of that angle must be negative because of position of the angle.

cos(3pi/4) = -√2/2
tan(3pi/4) = -1

Which graph represents a linear function?

A coordinate plane is shown with a curved line that starts in the bottom left area of the graph, passing through the point -1 comma -5, curving to pass through the y-axis at 2.5, then curving up again to pass through the point 1 comma 5

A coordinate plane is shown with a line passing through the x-axis at negative 2 and the y-axis at negative 6.

A coordinate plane is shown with a parabola graphed in an upward U shape. The bottom of the parabola touches the y-axis at -10 and curves upward on both sides

A coordinate plane is shown with a wavy line that sits on the x-axis and moves across the graph in even up and down waves.

Answers

A linear function is a straight line. Therefore, the answer is #2.

Answer:

2nd Option is correct.

Step-by-step explanation:

We are given with four statements which describes a graph of a function.

We need to find the graph which represents the linear function.

Linear Function:

Linear functions are the functions whose graph are straight lines.

A linear function has the following form

y = f(x) = a + bx

A linear function has one independent variable and one dependent variable. The independent variable is x and the dependent variable is y.

So, In graphs of 1st , 3rd and 4th Options are curves not a straight line.

Only 2nd Option has graph which is straight as mentioned in it that a line passing through two points.

Therefore, 2nd Option is correct.

if susie is fourteen, what was her age x years ago?

Answers

Well it depends on what x is or how many years ago, but the equation would be 14 - x = y y being the age x years ago.

Which size is better in buying detergent: 32 fl oz for $1.99
50fl oz for $2.49

Answers

the 32oz is more expensive per oz. by $.01 per oz.

HELP! A simplified version of sin2 θ (1 + cot2 θ) = 1 is ...?

Answers

The solution to the problem is as follows:

 LHS = sin^2 θ (1 + cot^2 θ) 
= sin^2 θ (1 + cos^2 θ/ sin^2 θ) 
= sin^2 θ + cos^2 θ 
= 1 
= RHS.

I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!

What's the numerator for the following rational expression? 8/y+3/y=?/y

Answers

ur answer would be 11/y
your answer is 11/y since the denominator is the same just add the 8 and 3  

What is the x-intercept of the line with this equation −2r+1/2 y=18?

Enter your answer in the box.
( ,0

Answers

to find the x int, we will sub in 0 for y and solve for x...um...r

- 2r + 1/2y = 18
-2r + 1/2(0) = 18
-2r = 18
r = -18/2
r = -9

so the x int is (-9,0)

state the degree x^3y^2+7x^2y^5-3xy^8

Answers

the main formula for a polynomial ax^my^n+...
the degree is the sum of the highest degree of the polynomial, it is m+n

the degree of  x^3y^2+7x^2y^5-3xy^8 is 9, because 3xy^8 is the term where we can find a highest value of power (8)
so the degree is degree of x, it is 1 + degree of y (it is 8)

Answer:9

Step-by-step explanation:

The area of one face of a cube is 7 cm2. what is its surface area?

Answers

The answer to this is 42 cm^3

Nicole deposits $2,136 in a savings account paying 5.36% interest. To the nearest dollar, how much money does Nicole have in total after nine years? a. $213 b. $1,030 c. $1,272 d. $3,166

Answers

we know that


The simple interest formula is equal to


[tex]A=P(1+rt)[/tex]


where


A is the Final Investment Value


P is the Principal amount of money to be invested


r is the rate of interest  

t is Number of Time Periods


in this problem we have


[tex]t=9\ years\\ P=\$2,136\\ A=?\\r=0.0536[/tex]


substitute in the formula above


[tex]A=2,136(1+0.0536*9)[/tex]


[tex]A=2,136(1.4824)[/tex]

[tex]A=\$3,166.41[/tex]  

Round to the nearest dollar

[tex]A=\$3,166[/tex]  

therefore

the answer is the option D

[tex]\$3,166[/tex]  

Write a justification for each step.

Answers

Step 1. Segment Addition Postulate

Step 2. Substitution

Step 3. Combine like terms

Step 4. Additive Property of Equality

Step 5. Subtraction Property of Equality

Step 6. Division Property of Equality

Find the greatest common factor of the following monomials.
21g^3h 45g^3h^2

Answers

I hope this helps you

The table lists the values for two parameters, x and y, of an experiment. What is the estimated value of x for y = 0.049?

a) 20.4
b) 21.4
c) 23.7
d) 24.7

Answers

Right answer is 20.4

yep 20.4 is the correct answer for plato!!

An elliptical track has a major axis that is 80 yards long and a minor axis that is 72 yards long. Find an equation for the track if its center is (0, 0) and the major axis is the x-axis.

Choices are in the attachment

Answers

Answer:

So basically it’s D

Step-by-step explanation:

:)

Explain a thought process you might use when trying to find the additive or multiplicative inverse of a number or expression. ...?

Answers

Definition of additive inverse.- If two numbers are added together and the sum is zero, they are the additive inverse of each other. 


......................................... IF A + B = 0 , they are the additive inverse of each other. 


Multiplicative Inverse.- If two numbers are multiplied together and the product is one. They are the multiplicative inverse of each other, also called reciprocal. 

......................................... A.B = 1 , they are the multiplicative inverse of each other. 


Example of: 

Additive inverses :................ 5 + ( - 5 ) = 0 

Multiplicative inverses...........5 x 1/5 = 1 
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