<PRE><B>Question 863807</B>
There are two equations to consider
S = x^2 + 4xy
V = x^2*y and V = 3600
y = V/x^2
S = (x^2 +4xy)
S = (x^2 +4*x*V/x^2)
dS/dx = 2x -4V/x^2
now set derivative to 0 for min surface area
2x = 4V/x^2
x^3 = 2V
x = (2V)^(1/3) = (7200)^1/3 = 19.31 cm
y = 3600 / x^2 = 3600 / 19.31^2 = 9.65 cm

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