# Thread: Rate of Change

1. ## Rate of Change

Got stuck on this one: Thanks!

Let f(x)=x(1-2x)
a. Find the average rate of change of f(x) with respect to x as x changes from x=0 to x=1/2
b.Find the instantaneous rate of change of f(x) at x =0

2. Originally Posted by lisa1984wilson
Got stuck on this one: Thanks!

Let f(x)=x(1-2x)
a. Find the average rate of change of f(x) with respect to x as x changes from x=0 to x=1/2
b.Find the instantaneous rate of change of f(x) at x =0
a. $\frac{f\left(\frac{1}{2}\right) - f(0)}{\frac{1}{2} - 0}$

b. $\lim_{x \to 0} \frac{f(x) - f(0)}{x - 0}$

where, exactly, are you "stuck" ?

3. I can get the first part but I'm not very good with the lim part don't know how to calculate it without a calculator!

4. Show us what you've done so far. The limit is very easy to figure out, so you should under no circumstances be using a calculator for it.

5. lim=f(x)-f(0)/x-0
lim= √x-0/x-0
lim=
√x-0/ (√x-0)( √x+0
lim=0/
√+1
lim=0/1=0

6. $f(x)=x(1-2x)$, so why are you using $f(x)=\sqrt{x}$?