TRY IT:
| Use the critter above to expand |  |
Let's use this new info to do some trickier problems.
| Let's find the 13th term in the expansion of |  |
... Without |
| pathetically trying to multiply it all out! |
OK, think about it...
The second variable... the 
...
The 
guy starts at 
and goes up one each time... So, at the
13th term, it will be
No more thinking left to do now!
Now, pop the coefficient:
