Differentials and derivatives help

Question

1. Use differentials to approximate the change in profit as X increases from 50 t0 51 units for the profit function p(x)=-0.5x^2 2500x-600

2. The value of the derivative for x^2y y^2= -2 at the point (-21,-1) is?

Answer 1

just differentiate them and sub in the values omg...