# This should be easy

1. Aug 21, 2008

### kenewbie

I'm certain I'm missing something obvious .. again.

I'm having trouble solving the following (using a pen and paper approach)

$$\frac{ 3^{12} - 3^{10} }{ 3^{11} + 3^{10} }$$

I've tried logarithms (I've only covered those with base 10 so far, so any log_n approach is disqualified), messing around with the exponents, roots and factoring, but I cant seem to find a way to do this without actually calculating the individual values.

k

Last edited: Aug 21, 2008
2. Aug 21, 2008

### Dick

Divide numerator and denominator by 3^10.

3. Aug 21, 2008

### HallsofIvy

Staff Emeritus
Or (same thing really) factor out a 310: 311= 310*3 and 312= 310*9
$$\frac{3^{12}- 3^{10}}{3^{11}- 3^{10}}= \frac{3^{10}(9- 1)}{3^{10}(3- 1)}$$

4. Aug 21, 2008

### kenewbie

aaah, sweet relief.

thank you.

k