9) h(y)= y^{2}- 1/y

Remember 1/y= y^{-1}

The derivative of 1/y is therefore -1y^{-2}

The derivative of y^{2}is 2y

You can then solve 2y - (-1y^{-2})= 0 for y

15) f(x)= pi - (x-2)2/3

Since pi is a constant the derivative of pi is 0

The derivative of (x-2)^{2/3}is (2/3)(x-2)^{-1/3}

So you can solve -(2/3)(x-2)^{-1/3}= 0 for x