Question

Can anyone help with a few calc questions?

A rectangular pare is to contain 81 square inches of print. The margins on each side are 1 inch. Find the dimentiond of the page such taht the least amount of paper is used.
A. 11,11
B.12,12
C. 13,13
D. 10,10

Find the differential of the function y=xcos(8x)
A. cos(8x)dx
B.-8xsin(8x)dx
C.cos(8x)-8xsin(8x)dx
D.(cos(8x)+8xsin(8x)dx

Answer 1

Also can you check a few.

Use Newton's Method to approximate the zero of the function f(x)=x^3+2x+2
I got -.7709

The measurement of the edge of a cube is found to be 5 inches with a possible error of .005 inch. Use differentials to estimate the propagated error in computing a the volume and b the surface area.
I got .375 cubic inches and .3 square inches

Answer 2

@Loser66

Answer 3

The second question would be

y=xcos(8x)
y'=x(-sin(8x)(8))+ cos(8x)
y'= cos(8x) - 8xsin(8x)

Answer 4

ok thanks. and the first one? I am thinking B

Answer 5

And I would assume that the first on is D, simply because 9x9=81, so if the page has 1inch margins, and 10-1=9, then wouldn't that use the least amount of paper??

Answer 6

can you check my other 2?

Answer 7

I did the math wrong orginaly, it would be a, because you lose 2 inches from the total width, not 1