00:02
So if we wanted to factor this polynomial to find the x intercepts, well, we can use the substitution method.
00:08
And so we say u is equal to x squared.
00:10
And so now we have u squared minus 5 u plus 4.
00:16
And so now we can factor this and say we have, well, what two numbers multiply to positive 4 and add up to negative 5? well, this would be negative 4 and 1.
00:27
And so we have u minus 4 and u minus 1.
00:33
And so now we can substitute in again x squared.
00:36
So we have x squared minus 4 and x squared minus 1.
00:42
And so we can use the difference of squares here to separate these.
00:46
So this would give us x minus 2 times x plus 2.
00:51
And then use the difference of squares again to get x minus 1 and x plus 1...