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# Partial differentiation question watch

1. f(x,y) = x^2 - y^3 +2xy^2

so partial differentiate, df/dy
= -3y^2 +4y

so df/dy (2,-1) = -7? my teacher got -11 so i dunno which is right
2. Your differentiation is incorrect. Think of 2xy^2 as a constant (2x) multiplied by y^2 - now try differentiating with respect to y again.

3. Treat x as a constant.

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Updated: September 26, 2010
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