L,w,h
area = 2 Lw + 2 Lh + 2wh = 600
so
Lw+Lh+wh = 300
but L = 3w
so
3 w^2 + 4 w h = 300
now
V = L w h = 3 w^2 h
so h = V/3w^2
3 w^2 + 4 w(V/3w^2) = 300
4 V/3w = 300 - 3 w^2
(4/3)V = 300 w - 3 w^3
we want d(4/3)V /dw = 0
300 = 9 w^2
w = (10/3)sqrt 3
L = 10 sqrt 3
w L = 100
so h = 6
check my arithmetic!
We want to construct a closed rectangular box whose base has a length three times the width. The surface area has to be 600 cm2. Determine the dimensions of the box that will produce the largest volume.
3 answers
Thank you!!!
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