What equation is equal to 3/8 less than a number is 11

Find the maximum and minimum values of the function f(x,y)=2x2+3y2−4x−5 on the domain x2+y2≤100. The maximum value of f(x,y) is:

ryzh [129]

First find the critical points of f :

$f(x,y)=2x^2+3y^2-4x-5=2(x-1)^2+3y^2-7$

$\dfrac{\partial f}{\partial x}=2(x-1)=0\implies x=1$

$\dfrac{\partial f}{\partial y}=6y=0\implies y=0$

so the point (1, 0) is the only critical point, at which we have

$f(1,0)=-7$

Next check for critical points along the boundary, which can be found by converting to polar coordinates:

$f(x,y)=f(10\cos t,10\sin t)=g(t)=295-40\cos t-100\cos^2t$

Find the critical points of g :

$\dfrac{\mathrm dg}{\mathrm dt}=40\sin t+200\sin t\cos t=40\sin t(1+5\cos t)=0$

$\implies\sin t=0\text{ OR }1+5\cos t=0$

$\implies t=n\pi\text{ OR }t=\cos^{-1}\left(-\dfrac15\right)+2n\pi\text{ OR }t=-\cos^{-1}\left(-\dfrac15\right)+2n\pi$

where n is any integer. We get 4 critical points in the interval [0, 2π) at

$t=0\implies f(10,0)=155$

$t=\cos^{-1}\left(-\dfrac15\right)\implies f(-2,4\sqrt6)=299$

$t=\pi\implies f(-10,0)=235$

$t=2\pi-\cos^{-1}\left(-\dfrac15\right)\implies f(-2,-4\sqrt6)=299$

So f has a minimum of -7 and a maximum of 299.

4 0

3 years ago

A rectangular prism has a length of 20 in a width of 2 in and a height of 3 1/4 in the prism is filled with cubes that have edge

Zinaida [17]

You can express the edge lengths in terms of "cubes" or you divide the total volume by the volume of a cube. It works either way.

Edge lengths are
.. 80 cubes by 8 cutes by 13 cubes
so total volume is
.. (80 * 8 * 13) = 8320 cubes

In cubic inches, the volume is
.. (20 in)*(2 in)*(3 1/4 in) = 130 in^3.
The volume of a 1/4-in cube is (1/4 in)^3 = 1/64 in^3.
Then the number of cubes that will fit in the prism is
.. (130 in^3)/(1/64 in^3) = 8320 . . . . cubes

8320 cubes are needed to fill the rectangular prism.

7 0

3 years ago

What is the slope and y-intrrcept of 5x-3y= -15

Ivahew [28]

5x - 3y= -15
3y = 5x + 15
y = 5/3 x + 5

answer

slope m = 5/3
y intercept = 5

4 0

3 years ago

Read 2 more answers

a person driving along the road moves rates of 56 miles per hour driven.How far does the person drive in 1.5 hours?

givi [52]

84 miles.
You just have to take half of 56 (28) and add it to 56 to get 84

8 0