- #1
evilpostingmong
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Homework Statement
Find the dimensions of a rectangular box with the largest volume with surface area 64cm^2.
Homework Equations
area of a rectangular prism 2xy+2yz+2xz
The Attempt at a Solution
took 2xy+2yz+2xz=64
rearranging for z:
z=(xy-32)/(y+x)
partial derivative of z with respect to x
y/(y+x)-(xy-32)/(y+x)^2
partial derivative of z with respect to y
x/(y+x) -(xy-32)/(y+x)^2
setting both derivatives equal to zero to obtain the critical point...
Here's where I hit a wall-
I cannot get a real root for y.
y/(y+x)-(xy-32)/(y+x)^2
y^2+xy=xy-32
y^2=-32
Please only help me up to this point until I ask you to help me further, I
want to challenge myself. Thank you!