00:01
Okay, we're going to use composition to show that these two things are, these two functions are inverses.
00:06
So what we know is that if we find f of f inverse of x and f inverse of x, and we get them both to equal x, then f of x and f inverse of x are inverses.
00:27
So that's using composition.
00:29
So remember, you might have seen composition before.
00:32
As like f of g of x or g of f of x.
00:37
So that's composition.
00:38
But here we have, instead of f of x and g of x, we have f of x and f inverse of x.
00:46
Okay, so first we're gonna find f of f inverse of x.
00:53
So we know that f of x equals 7 eighths x.
01:00
So we're plugging f inverse of x in for x.
01:06
So we're finding f of 8 .7x equals 7x times 8 .8x.
01:17
And actually, i'm going to do these in different colors, so you can kind of see exactly what i did there.
01:23
Okay, so all i did was i took what we had written in the line above, and i replaced this x with f inverse.
01:36
So then i replaced this x with f inverse...