# Thread: Average rate of change

1. ## Average rate of change

So how would i find the answer to this if:
A and B are points on the graph of f(x) = 1 / x^2. The x-coordinate of point A is 5 and the x-coordinate of point B is 5 + h. Find the average rate of change of f on the interval [5, 5 + h]? P.S. this is a practice problem, thanks!

2. Average rate of change in this instance is $\displaystyle \frac{f(b)-f(a)}{b-a}=\frac{\frac{1}{(5+h)^2}-\frac{1}{5^2}}{(5+h)-5} = \dots$

Can you finish it?

3. Originally Posted by pickslides
Average rate of change in this instance is $\displaystyle \frac{f(b)-f(a)}{b-a}=\frac{\frac{1}{(5+h)^2}-\frac{1}{5^2}}{(5+h)-5} = \dots$

Can you finish it?
I don't know if this is right, but i got: 10 + h / 25(5+h)^2

4. I get $\displaystyle \frac{-10-h}{25(5+h)^2 }$ you might have dropped a minus somewhere.

5. Originally Posted by pickslides
I get $\displaystyle \frac{-10-h}{25(5+h)^2 }$ you might have dropped a minus somewhere.
Oh I think I know where I've went wrong now, thanks a lot!