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MathTooHard Suppose f is a differentiable function of x and y, and g(r,s) = f(2r-s,s^2-4r). Calculate dg/dr at (1,2) and dg/ds at (1,2) given that f(1,2)=6, g(1,2)=3, df/dx(1,2)=2 and df/dy(1,2)=5.
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