00:01
So in this question, they give us a function f of x, and f of x is equal to 2x squared minus 8x plus 7, and i want to find an f of the quantity of x minus 3.
00:15
So how does that work? remember, functions are all about substitution.
00:21
So if i want f of the quantity of x minus 3, everywhere i see an x, i'm going to replace it with the quantity of x minus 3.
00:30
So that i have two times the quantity of x minus 3 being squared minus 8 times the quantity of x minus 3.
00:41
And to this i'm adding 7.
00:44
And so i'm going to go ahead, multiply this out, and combine like terms.
00:49
So what do you get if you square out x minus 3 quantity squared? well, x minus 3 quantity squared is x squared minus 6x plus 9.
01:01
If i distribute my negative 8, i'm getting negative 8x plus 24.
01:09
And to that, i'm adding 7.
01:12
Now, i'm going to distribute the 2 into that first trinomial.
01:17
When i do, i get 2x squared minus 12x plus 18, minus 8x, plus 24, plus 7.
01:29
And so, combining my like terms, f of x minus 3, i'm getting 2x squared...