The rule for differentiating a simple equation such as this is, to times the coefficient by the power and the take one away from the power. Therefore, lets look at 5x^4 you would times the 5 by 4 to get 20x^4 and then you would take away one from the power so that it would be 20x^3. Follow this rule for 16x^2 to get 32x and then the 4x, when differentiated would just equal 4. The 5 would disappear when differentiating because you are differentiating the equation in terms of x and there is no x attached to the 5. So, the final answer would be f'(x)= 20x^3 + 32x +4