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December 20, 2014

December 20, 2014

Posted by **soraya** on Sunday, November 14, 2010 at 6:47pm.

- calculus -
**Reiny**, Sunday, November 14, 2010 at 8:08pmlet the base be x by x

let the height be y

V = x^2y

20 = x^2y

y = 20/x^2

cost = 30x^2 + 4(10)xy + 20x^2

= 50x^2 + 40x(20/x^2)

= 50x^2 + 800/x

d(cost)/dx = 100x - 800/x^2

= 0 for min cost

100x^3 = 800

x = (8)^(1/3) = 2

y = 20/(2)^2 = 5

check my calculations.

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