1) Find all x-coordinates of points (x,y) on the curve

y=(x6)3(x7)4

where the tangent line is horizontal.

2) If y=x2+45, find d2y/dx2.

3)

A function h(x) is defined in terms of a differentiable f(x). Find an expression for h'(x). f(x ) h(x) = x4+9