(a) By first calculating partial derivatives of the exponentiation function f(x, y) = xy", show that if z=f(x, y), then 2 2 1 ( + ) + 1 (A^) * . Az = 2 m (b) By first calculating partial derivatives of the exponential function f(x,y)=x", show that if z=f(x,y), then Ar 2 2 A= = = /2 (+ ) + (+) (+) . In(2) (c) By first calculating partial derivatives of the logarithmic function f(x, y) = log,(r), show that if z=f(x,y), then Az = z In(x) (A) . 2 1 + In(y) (+) .