# Thread: What should I do??

1. ## What should I do??

2. Originally Posted by Alienis Back
isn't $r$ the rate of interest? just plug in $r = 0.12$ (the decimal equivalent of 12%) and calculate

3. ## That's a great help

Now how do I factor the right side?
Just give me a clue.

4. Originally Posted by Alienis Back
Now how do I factor the right side?
Just give me a clue.
it should be $1 + r + \frac {r^2}4$ in the brackets, right?

if so, first factor out the 1/4, you get $\frac 14 (4 + 4r + r^2) = \frac 14(r^2 + 4r + 4)$

now, can you factor the inside? you should be able to