00:01
Here, we're given a function q of x, which is equal to x squared plus 9x plus 15.
00:08
And first we want to ask if we can write this in vertex form.
00:12
So to write this in vertex form, we could complete the square.
00:15
I find that i want to avoid completing the square at all costs, though.
00:19
So i'm not going to do that.
00:20
Instead, i'm going to use that x equals negative b over 2a is the vertex.
00:26
So negative 9 over 2 is the vertex.
00:30
Now that i know the vertex, i know that q of x will be equal to a, which is the same a as we originally had.
00:37
So 1 times x minus 9 halves, because that's the vertex squared, plus some k value...