# Thread: Help with a Limit Problem

1. ## Help with a Limit Problem

I don't understand how to go about doing this problem:

The limit of numerator (1/3 + deltaX)^2 - (1/9) divided by denominator deltaX as deltaX approaches 0.

Any help will be much appreciated!

2. Use this $\left( {\frac{1}{3} + \Delta x} \right)^2 - \frac{1}{9} = \frac{{2\Delta x}}{3} + \left( {\Delta x} \right)^2$.

3. Originally Posted by Plato
Use this $\left( {\frac{1}{3} + \Delta x} \right)^2 - \frac{1}{9} = \frac{{2\Delta x}}{3} + \left( {\Delta x} \right)^2$.
What happens to the 1/9?

4. Originally Posted by blurain
What happens to the 1/9?
It goes away because you have (1/9) - (1/9) = 0.