00:01
We want to factor the trinomial 3x squared minus 7x minus 48.
00:07
Since this is a trinomial with a leading coefficient that is not 1, we multiply the 3 times the negative 48.
00:14
And 3 times negative 48 is negative 144.
00:19
That's our target number.
00:22
Our clue here is that one of these terms have to be positive and negative to multiply to a negative.
00:29
And if we add to a negative, the larger one must be negative.
00:33
So we think about all the different ways we can get 144.
00:37
Starting with something like 72 and 2, it would be 2 in negative 72 because the negative, since we add to a negative, that is not negative 7.
00:51
So does 3 go into it? yes, it does.
00:55
It would be 3 and negative 48.
00:59
That does not make negative 7.
01:01
What about 4? that would be 4 and negative 36, also not 7.
01:08
5 does not go into 144...