Thread: rate of change type

Let f(x) = root x. If the rate of change of f at x = c is twice its rate of change at x=1, then c=...?

i have no idea what to do.

Originally Posted by abcocoa

Let f(x) = root x. If the rate of change of f at x = c is twice its rate of change at x=1, then c=...?
i have no idea what to do.

Hello,

the rate of change is calculated by the first derivative:



Now calculate f'(1) = 1/2. That means you know now the value of the rate of change at c: It is 1. Therefore solve the following equation for c:

. I've got

EB