00:01
Hello, so here we have 4x cubed, minus 4x squared, minus 21x, minus 9.
00:04
Or if we factor that, by the factor theorem, we get 2x plus 1 times the quantity 2x plus 3 times the quantity x minus 3.
00:12
And we can check that.
00:13
Because we multiply 2x plus 1 times 2x plus 2x, well, we get 2x times 2x, that's 4x squared, 2x times 3.
00:19
It's going to be about 6x, but then plus 2x because it's plus 8x, and then 1 times 3 is 3.
00:24
Then you multiply that quantity by x minus 3.
00:27
So at the x minus three distributes here, we get x times 4x squared, it's going to be 4x cubed, and then x times 8x, so that's plus 8x squared, and then x times 3 is going to be plus 3x, and then negative 3 distributes with negative 3 times 4x squared is negative 12x squared.
00:45
Negative 3 times 8 is minus 24x, negative 3 times 3 is minus 9...