Find the absolute maximum and minimum values of the function f(x, y) = x2 + xy + y2 on the disc x2 + y2 ≤ 1

Answers

Answer 1
[tex]f(x,y)=x^2+xy+y^2[/tex]
[tex]\dfrac{\partial f}{\partial x}=2x+y[/tex]
[tex]\dfrac{\partial f}{\partial y}=2y+x[/tex]

Critical points occur when both partial derivatives vanish; this happens when

[tex]\begin{cases}2x+y=0\\2y+x=0\end{cases}\implies x=0,y=0[/tex]

The function has Hessian

[tex]\mathbf H(x,y)=\begin{bmatrix}\dfrac{\partial^2f}{\partial x^2}&\dfrac{\partial^2f}{\partial x\partial y}\\\\\dfrac{\partial^2f}{\partial y\partial x}&\dfrac{\partial^2f}{\partial y^2}\end{bmatrix}=\begin{bmatrix}2&1\\1&2\end{bmatrix}[/tex]

which at [tex](0,0)[/tex] has [tex]\det\mathbf H(0,0)=3>0[/tex]. And since [tex]\dfrac{\partial^2f}{\partial x^2}\bigg|_{x=0,y=0}=2>0[/tex], it follows that a local minimum occurs at [tex](0,0)[/tex] with a value of [tex]f(0,0)=0[/tex].

Meanwhile, we can parameterize the boundary by

[tex]\begin{cases}x=\cos t\\y=\sin t\end{cases}[/tex]

with [tex]0\le t\le2\pi[/tex]. So

[tex]f(x,y)=f(x(t),y(t))=F(t)=\cos^2t+\sin t\cos t+\sin^2t=1+\dfrac12\sin2t[/tex]

which has critical points when [tex]F'(t)=0[/tex]:

[tex]F'(t)=\cos2t=0\implies 2t=\dfrac\pi2+n\pi\implies t=\dfrac\pi4+\dfrac{n\pi}2[/tex]

We only have 4 points to worry about: [tex]t=\dfrac\pi4,\dfrac{3\pi}4,\dfrac{5\pi}4,\dfrac{7\pi}4[/tex]

Now,

[tex]F\left(\dfrac\pi4\right)=\dfrac32[/tex]
[tex]F\left(\dfrac{3\pi}4\right)=\dfrac12[/tex]
[tex]F\left(\dfrac{5\pi}4\right)=\dfrac32[/tex]
[tex]F\left(\dfrac{7\pi}4\right)=\dfrac12[/tex]

So we find that an absolute minimum occurs at [tex](0,0)[/tex] with a value of [tex]0[/tex], and two more extrema occur along the boundary when [tex]t=\dfrac\pi4[/tex] and [tex]t=\dfrac{5\pi}4[/tex], i.e at the points [tex]\left(\dfrac1{\sqrt2},\dfrac1{\sqrt2}\right)[/tex] and [tex]\left(-\dfrac1{\sqrt2},-\dfrac1{\sqrt2}\right)[/tex], both with the same maximum value of [tex]\dfrac32[/tex].

Related Questions

Consider the equation 3p – 7 + p = 13. What is the resulting equation after the first step in the solution?

Answers

3p - 7 + p = 13... simplify
4p - 7 = 13....add 7 to both sides
4p = 13 + 7
4p = 20 ...divide both sides by 4
p = 20/4
p = 5

Gio is solving the quadratic equation by completing the square 5x^2+15x-4=0 What's should gio do first?

Answers

Gio should first complete the square by adding and subtracting [tex]\((\frac{3}{2})^2\)[/tex], leading to the equation [tex]\((x + \frac{3}{2})^2 = \frac{25}{4}\).[/tex]

To solve the quadratic equation [tex]\(5x^2 + 15x - 4 = 0\)[/tex] by completing the square, Gio should follow these steps:

1. Make the Coefficient of [tex]\(x^2\) 1:[/tex]

Divide the entire equation by the coefficient of [tex]\(x^2\)[/tex] to make it equal to 1. In this case, divide the equation by 5:

[tex]\[x^2 + 3x - \frac{4}{5} = 0.\][/tex]

2. Move the Constant to the Other Side:

Move the constant term to the other side of the equation:

[tex]\[x^2 + 3x = \frac{4}{5}.\][/tex]

3. Complete the Square:

  Add and subtract [tex]\((\frac{3}{2})^2\)[/tex] inside the parentheses to complete the square:

 [tex]\[x^2 + 3x + (\frac{3}{2})^2 = \frac{4}{5} + (\frac{3}{2})^2.\][/tex]

4. Factor the Perfect Square Trinomial:

  Factor the left side, which now is a perfect square trinomial:

 [tex]\[(x + \frac{3}{2})^2 = \frac{25}{4}.\][/tex]

5. Solve for (x):

  Take the square root of both sides and solve for (x):

[tex]\[x + \frac{3}{2} = \pm \frac{5}{2}.\][/tex]

6. Isolate (x):

  Isolate (x) on one side to find the solutions:

  [tex]\[x = -\frac{3}{2} \pm \frac{5}{2}.\][/tex]

Therefore, Gio should first complete the square by adding and subtracting [tex]\((\frac{3}{2})^2\)[/tex], leading to the equation [tex]\((x + \frac{3}{2})^2 = \frac{25}{4}\).[/tex]

what is 3/4 of 535?????????

Answers

Whenever they ask what is a certain fraction of a number, just multiply.
(3/4)(535)=401.25
It might be 401.25 I’m not sure

Car X leaves Northtown traveling at a steady rate of 55 mph.  Car Y leaves 1 hour later following Car X, traveling at a steady rate of 60 mph.  Which equation can be used to determine how long after Car X leaves Car Y will catch up?

Answers

The equation that can be used to determine how long after Car X leaves Car Y will catch up is D. 55x = 60(x - 1).

To determine when Car Y will catch up to Car X, we need to find the time it takes for Car Y to cover the same distance as Car X. Since Car Y leaves 1 hour later, it will travel for (x - 1) hours, where x represents the time Car X has been traveling. So, the equation would be:

D. 55x = 60(x - 1)

This equation accounts for the distance traveled by both cars over the same time frame, considering Car Y started an hour later.

Complete question : Car X leaves Northtown traveling at a steady rate of 55 mph. Car Y leaves 1 hour later following Car X, traveling at a steady rate of 60 mph. Which equation can be used to determine how long after Car X leaves Car Y will catch up? A. 55x=60x-1 B.55x=60x C.60x=55x(x-1) D.55x=60(x-1).

Need help with this problem
Scott has fees taken out of his bank account each month for 3 months. A total of $12 is taken from his bank account.

Drag the numbers to form the equation that represents the change in Scott's bank account each month.

( ? )( ? ) = ( ? )

3, -3, 12, -12, 1/3, -1/3, 4, -4

Show work

Answers

The blanks would be -4*3=-12.

The numbers will be negative because there is an subtraction happening.

work shown: -4+-4+-4=-12

Please vote my answer brainliest. thanks!

how do you solve for 2w+8=-3+2w

Answers

2w + 8 = -3 + 2w
2w - 2w = -3 - 8

0 = -11

this equation is unsolvable, because -11 ≠ 0

hope this helps

Vanessa made 6 sandwiches for a party and cut them all into fourths. How many 1/4 sandwich pieces did she have?

Answers

She had 24 pieces.

6 / (1/4) = 24

Determine the discriminant for the quadratic equation 0 = –2x2 + 3. Based on the discriminant value, how many real number solutions does the equation have?

Discriminant = b2 – 4ac


real number solutions

Answers

Determine the discriminant for the quadratic equation 0 = –2x2 + 3. Based on the discriminant value, how many real number solutions does the equation have?  Remember that the discriminant is calculated using the coefficents a, b and c.  Given 0 = -2x^2 + 0x + 3, the coeff. are a=-2, b=0 and c=3.

The discriminant is b^2 - 4ac.  Here, the discriminant is 0^2 - 4(-2)(3) = 24.

Since the discriminant is positive, you have two real, unequal roots.

The positive value of the discriminant implies that there are two real unequal roots and this can be determined by using the formula of the discriminant.

Given :

The quadratic equation is [tex](0=-2x^2+3)[/tex].

The following steps can be used in order to determine the total number of real solutions does the equation have:

Step 1 - Write the given quadratic equation.

[tex]0=-2x^2+0x+3[/tex]

Step 2 - The formula of discriminant is given below:

[tex]D = b^2-4ac[/tex]

where 'b' is the coefficient of 'x', 'a' is the coefficient of [tex]x^2[/tex], and 'c' is the constant.

Step 3 - Now, substitute the values of a, b, and c in the above formula.

[tex]D = (0)^2-4\times (-2)\times 3[/tex]

[tex]D = 24[/tex]

Step 4 - The positive value of the discriminant implies that there are two real unequal roots.

For more information, refer to the link given below:

https://brainly.com/question/12657401

Solve. 54 ÷ (4 – 1)3

Answers

54 divide 3*3=54 is the answer
distribute the numbers so 54 divide (4-1)3 ,  3 x 4= 12-3=9, then 54 divided by 9 equals 6

Factor the difference of two cubes

Answers

Since 216=6^3, and (a – b)(a^2 + ab + b^2) is how to factor the difference of a cube (that's the formula), we have (6-x)(6^2+6x+x^2)=(6-x)(36+6x+x^2)

A 33 - m tall building casts a shadow. The distance from the top of the building to the tip of the shadow is 37 m . Find the length of the shadow. If necessary, round your answer to the nearest tenth.

Answers

This is Pythagorean theorem, a^2+b^2=c^2 , a = 33 and c = 37 so b^2 + 1089 = 1369 , b^2 = 280 , b = 16.73m
Final answer:

To solve this, we use Pythagoras' theorem as we have a right-angled triangle formed by the building, its shadow and the line between the top of the building to the end of the shadow. We find that the length of the shadow is approximately 16.7 meters.

Explanation:

To solve this problem, we need to apply Pythagoras' theorem because the building, the shadow and the line between the top of the building to the end of the shadow form a right-angled triangle.  

Pythagoras' theorem states that in a right-angled triangle, the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides. This can be written as:

a² + b² = c²

In this scenario, the height of the building is one side of the triangle (a), the shadow is the other side (b), and the line from the top of the building to the tip of the shadow is the hypotenuse (c).

So, to find the length of the shadow, we rearrange the formula to solve for b:

b = sqrt(c² - a²)

Then, we substitute the known values:

b = sqrt( (37m)² - (33m)²) = sqrt(1369 - 1089) = sqrt(280) = 16.7m

So, the length of the shadow is approximately 16.7 meters.

Learn more about Pythagoras' theorem here:

https://brainly.com/question/343682

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can someone please help me with using the quadratic formula to find the solutions to the equation

Answers

A quadratic equation has the standard form:

ax^2 + bx + c = 0

in the given equation,
a = 3
b = -10
c = 5

plug these values into the quadratic formula.

(-b +/- sqrt(b^2 - 4ac)) / (2a)

(-(-10) +/- sqrt((-10)^2 - 4(3)(5)) / (2*3)
(10 +/- sqrt(100 - 60)) / (6)
(10 +/- sqrt(40)) /6

What is 7 to the 4 world power in expanded form?

Answers

"world" power ???

Don't you mean "what is 7 to the 4th power?"

It's (7)(7)(7)(7) = (49)(49), or approx. 2,500.  Multiply out 49(49) for the exact answer.

Which expression is the factorization of x2 + 10x + 21?

A) (x + 3)(x + 7)
B) x + 4)(x + 6)
C) (x + 6)(x + 15)
D) (x + 7)(x + 14)

Answers

the answer is              A
hoped this helped!
its choice A because when you distribute or foil you will get x2 + 10x + 21

Anyone know the answer to these problems?
Explain with steps
Correct answer will receive Brainliest

Answers

Find the value of the expression we use the following rules of the exponents:

[tex]\displaystyle{ i) \frac{a^b}{a^c}=a^{b-c}[/tex]  for b>c
[tex]\displaystyle{ ii)\frac{a^b}{a^c}=\frac{1}{a^{c-b}}[/tex]    for c>b


Using these 2 rules, we have: 

[tex]\displaystyle{( \frac{(10^4)(5^2)}{(10^3)(5^3)} )^3=( \frac{10^{4-3}}{5^{3-2}} )^3= (\frac{10}{5})^3=2^3=8 [/tex]

The sum of two consecutive integers is 65. Find the two integers.

Answers

32+33=65 
60/2 is 30, so they have to be in their thirties. Then 2+3=5, therefore they must be 32 and 33

Margaret uses 1 3/4 teaspoons of vanilla to make 12 cupcakes. She to wants make 30 cupcakes. how much vanilla will Margaret use?

Answers

12 ×2=24+ 6 =30
1 3/4 + 1 3/4+ half of that 7/8
total teaspoons 4 3/8

To make 30 cupcakes Margaret needs 4.375 cups of vanilla.

What are the ratio and proportion?

The ratio is the division of the two numbers.

For example, a/b, where a will be the numerator and b will be the denominator.

Proportion is the relation of a variable with another. It could be direct or inverse.

Given that,

Margaret uses 1 3/4 teaspoon of vanilla to make 12 cupcakes

So,

1 3/4 teaspoon vanilla ⇒ 12 cupcakes

(4×1 + 3)/4 teaspoon ⇒ 12 cupcakes

7/4 teaspoon vanilla ⇒  12 cupcakes

Divide by 12 into both sides,

7/(4×12)  teaspoon vanilla ⇒ 1 cupcake

Now multiply by 30 on both sides,

(7 × 30)/(4 × 12)teaspoon vanilla ⇒ 30 cupcake

30 cupcakes ⇒ 4.375 teaspoon vanilla.

Hence "To make 30 cupcakes Margaret needs 4.375 cups of vanilla".

For more information about ratio and proportion,

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DIVIDING ALGEBRAIC FRACTIONS

2p/4p^2 divided by 6p^3/6p+3

Answers

To multiply two fractions, you multiply the numerators together and you multiply the denominators together
= 2p(6p + 3) / 6p^3(4p^2 - 1)

Next, we can factor out a 3 in the numerator
= 6p(2p + 1) / 6p^3(4p^2 - 1)

Next, we can factor the denominator
= 6p(2p + 1) / 6p^3(2p - 1)(2p + 1)

Since we have (2p + 1) in the top and bottom, we can cancel it
= 6p / 6p^3(2p - 1)

We can also cancel a 6p in the top and bottom
Answer: 1 / p^2(2p - 1)

hope I helped

The population of a city in Alabama increases every year by 11.5 percent. If the population in 2011 was 4.8 million, what will its population be in 2016?
A)2.6 million
B)2.76 million
C)8.27 million
D)220 million

Answers

8.27 million
4.8*(1.115)[tex] ^{5} [/tex]

Which expression results when the change of base formula is applied to log4(x+2) ?

Answers

Answer-

[tex]\frac{\log (x+2)}{\log 4}[/tex] is the correct answer.

Solution-

The formula for change of base in logarithm is given by,

[tex]\log_{b}a=\frac{\log_{c}a}{\log_{c}b}[/tex]

If we take the common base as 'e' , the formula becomes,

[tex]\log_{b}a=\frac{\log a}{\log b}[/tex]

Applying this formula,

[tex]\log_{4}(x+2)=\frac{\log (x+2)}{\log 4}[/tex]

∴ As the first option matches with our answer, hence it is the correct answer.

( In the fourth option a bracket is missing, so it is not the correct option)

Order these fractions from greatest to least. 4/9 , 4/10 , 4/5

Answers

4/9 = 0.4 with a line over the 4 because it is repeating
4/10 = 0.4...same as 0.40
4/5 = 0.8

least to greatest : 4/10, 4/9, 4/5
Well first you have to find the common denominator for all of them so the common denominator should be 90 

So then 40/90, 36/90, 72/90
So here is the answer: 4/5, 4/9, 4/10
Hope this was a good answer :)     

And sorry it took me so long.

What is the answer to 8=56, 7=42, 6=30, 5=20, 3=?

Answers

8(7) = 56
7(6) = 42
6(5) = 30
5(4) = 20
4(3) = 12
3(2) = 6
∴ 3 = 6

Step by step how to factor:
2y^2+9y+9=0

Answers

use ac method
for ax²+bx+c=0 when a≠1


multiply a and c, let's call the product r
what 2 numbesr multiply to get r and add to get b


2y²+9y+9=0
2*9=18
wat 2 numbers multiply to get 18 and add to get 9
3 and 6
split it up to that

2y²+3y+6y+9=0
group
(2y²+3y)+(6y+9)=0
factor
y(2y+3)+3(2y+3)=0
undistribute
(y+3)(2y+3)=0
set to zero

y+3=0
y=-3

2y+3=0
2y=-3
y=-3/2


y=-3 and -3/2
it's factored form is (x+3)(2x+3)

carl puts $1.10 in his piggy bank everyday in month of July (31 days)his total saving was $55.00 at the end of June what is the best estimate for his savaging at the end of June

Answers

At the end of July, Carl put $34.10 into his piggy bank, this means he had $15.90 in the piggy back to begin the month
multiply by the number of days in july ($1.10 x 31 = 34.10)

subtract July's amount (34.10) from the total

55.00 - 34.10 = 20.90

he had $20.90 at the end of June. Hope this helps!

!!PLEASE HELP!!
After school, Mike spends from 4:00 to 6:00 doing homework, eating, and playing sports. If he spends 65 minutes on homework and 15 minutes on eating, how much time does he have to play sports?

Answers

your answer would be 40. there are 60 minutes in an hour 60*2= 180
 add 65 and 15 together and subtract that from 180 and you will get your answer
4:00 to 6:00 would be two hours, or 120 minutes (2 hours*60 minutes per hour)
120 minutes-15 minutes, eating-65 minutes, homework=120-15-65
120-15=105
105-65=40
Mike would have 40 minutes to play sports

Is the value 75+(-75) less than zero, equal to zero, or greater than zero?

Answers

75 - 75 = 0, therefore, your answer is equal to zero

hope this helps

If one inch represents 8 feet, what dimensions would you use to make a scale drawing of a building 34 feet by 75 feet?
Please answer and explain!

Answers

4 inches by 9.375 is the answer because you divide the both numbers by 8

Find the sum of 914 and 878

Answers

Sum refers to the answer of an addition problem. So:

914 + 878
1792

Hope this helps!
802492 If Multiplying && 1792 If Adding

Estimates 3 2/3 \ 3 2/9

Answers

hello  
3 2/3 \ 3 2/9
(32/3) × (9/32) = 9/3=3

A sum of money is invested at 12% compounded quarterly. About how long will it take for the amount of money to double?

Compound interest formula: (image uploaded V(t) )

t = years since initial deposit
n = number of times compounded per year
r = annual interest rate (as a decimal)
P = initial (principal) investment
V(t) = value of investment after t years

A. 5.9 years
B. 6.1 years
C. 23.4 years
D. 24.5 years

Answers

Follow the given formula.  The initial amount of money invested, P, becomes 2P (same thing as "doubles) after t years.  Since compounding is quarterly, n=4.  The annual interest rate is 12%.  That is, r=0.12.

Then we have 2P = P (1 + 0.12/4)^(4t) and need only solve for time, t.

Simplifying the above equation:  2 = (1.03)^(4t)

We must isolate 4t, and then isolate t.  To do this, take the common log of both sides of the above equation.  We get:

log 2 = (4t) log 1.03.  This gives us 4t = [log 2] / [log 1.03], or

4t =  23.4498

Dividing both sides by 4, we get     t = 5.86 (years).

Compound interest is the interest generated overtime on a sum of money invested. The time it will take for the amount of money to double is 5.9 years

How to calculate the compound interest?

Compound interest is the interest generated overtime on a sum of money invested. The formula for calculating compound interest is expressed as:
V(t) = P(1+r/n)^nt

where:

t = years since initial depositn = number of times compounded per yearr = annual interest rate (as a decimal)P = initial (principal) investmentV(t) = value of investment after t years

Given the following

V(t) = 2P
r = 0.12
n = 4

Substitute
2P = P(1+0.12/4)^4t
2 =  (1.03)^4t
ln2 = 4t ln(1.03)
0.6931 = 0.1182t
t = 0.6931/0.1182
t = 5.9 years

Hence the time it will take for the amount of money to double is 5.9 years

Learn more on compound interest here: https://brainly.com/question/24924853

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