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December 21, 2014

December 21, 2014

Posted by **julie** on Sunday, January 6, 2008 at 6:31pm.

find the minimum value of xy.

find the rate of change of xy with respect to x.

find the rate of change of xy with respect to y.

- calculus -
**Damon**, Sunday, January 6, 2008 at 6:50pmf(x,y) = xy = x (4x-3)

f = 4 x^2 - 3x

df/dx = 8 x - 3

that is 0 when x = 3/8 and the second derivative is positive so it is a minumum

then x y = (3/8)(3/2 -3)

= (3/8) (-3/2) = -9/16

we found df/dx

now df/dy

4x = y+3

x = (y+3)/4

g(y) = xy = y(y+3)/4

= (1/4)(y^2+3y)

dg/dy = (1/4)(2 y+3)

= y/2 + 3/4

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