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December 19, 2014

December 19, 2014

Posted by **Marie** on Monday, April 23, 2012 at 7:45pm.

- Calculus -
**Damon**, Monday, April 23, 2012 at 8:17pmfinally I get to use calculus for this problem instead of completing square!

length total = 6 x

width = y

fencing = 7 y + 12 x = 480

so

y = (480-12x)/7

A = 6 x y

A = 6 (x)(480-12 x)/7

A = (6/7) (480 x - 12 x^2 )

dA/dx = (6/7)(480 - 24 x) = for max

24 x = 480

x = 20

then y = 240/7 = 34.3 approx

A = 6 x y = 6 * 20 * 240/7 = 4114.3

- Calculus -
**Damon**, Monday, April 23, 2012 at 8:19pmI have done many of these fencing problems tonight but most were in algebra where I had to find the vertex of the parabola by completing the square instead of taking the derivative and setting it to zero. Using Calculus makes it much much easier.

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