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For the function `f(x,y)=8*log(3x+7y)`, note that `f(100,100)=38`.

Give exact answers.

(a) Find `f_{x}(100,100)`=  

(b) Find `f_{y}(100,100)`=  

(c) Find the expression for the linear approximation to the function at the point `(100,100)`.  

(d) Use the expression for the linear approximation to approximate `8*log(1012)=f(104,100)`.