# Math Help - f(x) to f'(x) help

1. ## f(x) to f'(x) help

Hey guys! I have a problem. the following picture shows a question on a test i had. I understand how to do part i) and part ii), but I'm not sure how to do part iii). specifically, i don't understand how they got from n(x) to N'(x)

i understand how they went from $100x - 100x^4$ to $100(4)x^3$ but what happened to the 2000?

2. The derivative of a constant is zero.

3. Our lecturer urged us to do mental gymnastics. "In the morning, pick a constant", he would say, "and differentiate it. Next day, pick a bigger constant".