00:01
For this problem, we've been given the function, f of x equals 5x squared minus 4x plus 11.
00:07
And we want to compute the difference quotient, which is f of x plus h minus f of x over h.
00:16
This difference quotient is something that we're going to see repeatedly throughout calculus.
00:21
So when we go to evaluate this, you notice we have the function f being referred to twice in our numerator.
00:28
The second time, it's just plainer.
00:30
Old f of x.
00:31
The first time, though, is f of x plus h, which means that in our function, every time we see x, we're going to replace it with x plus h.
00:40
So let's do that.
00:41
Let's substitute in and see what we have for our fraction.
00:46
First of all, f of x plus h.
00:48
That's 5 times x plus h squared, minus 4 times x plus h plus 11.
00:56
And now i'm going to subtract f of x.
01:00
5x squared.
01:01
Minus 4x plus 11.
01:03
We are subtracting that entire thing, so you do have to have parentheses...