math
posted by srishti on .
A box must have base x cm by 2x cm. what are the dimensions of the box of maximum volume if its length+width+depth<140cm

2 x^2 h = v
h = 1403x
v =2 x^2 (1403x)
v = 280 x^2  6 x^3
dv/dx = 0 = 560 x  18 x^2
x(560  18x) = 0
18 x = 560
x = 31.1
2x = 62.2
h = 140  3(31.1) = 46.7