00:01
Okay, and this problem is computing the binomial expansion of 2x minus 3y cubed.
00:07
So we compare this to our standard binomial formula, which is a plus b to the power n.
00:14
We can see that our a is 2x, our b is negative 3y, and our n is 3.
00:21
So we'll need the third row of our pascal's triangle, which should be this one right here.
00:28
So we'll take those numbers in a minute.
00:31
We'll start on this expansion.
00:32
So i like to leave blanks from my binomial coefficients.
00:36
So i have 2x all cubed.
00:38
Notice i use a parentheses here.
00:41
2x squared times negative 3y to the power 1 plus something times 2x to the power 1, negative 3y squared plus something 2x to the power 0, negative 3y cubed.
01:00
Okay.
01:01
Now what goes on all these blanks? that's just my binomial coefficient.
01:04
So 1, 3, 3, 1.
01:08
And then from here, i can start simplifying each of these terms.
01:11
I'm going to distribute this 3 onto both of these terms right here...