00:02
Okay, we're going to confirm that f and g are inverses by showing that f of g of x and g of x are both equal to x.
00:09
So we're going to do f of g of x.
00:15
So that's f of and then g of x is 2x plus 3 over x minus 1.
00:23
So we're going to put that into the f function.
00:26
So that's going to be 2x plus 3 over x minus 1 plus 3 over 2x minus 1 plus 3 over 2x plus 3 over x minus 1 minus 2.
00:41
Okay, we need to simplify this.
00:42
So the first thing to do is multiply the top and bottom by x minus 1.
00:47
This just creates an equivalent fraction, so i haven't changed the value.
00:53
Okay, so if we multiply that out, it's going to cancel the x minus 1 in the first term to give 2x plus 3.
00:59
And then i need to multiply 3 with x minus 1.
01:04
Okay, and the bottom, it's going to cancel out the denominator.
01:08
In the first term and then i need to multiply with negative 2.
01:13
So that's 2x plus 3, multiplying the 3 out, we get plus 3x minus 3.
01:20
The bottom is 2x plus 3, multiplying out is minus 2x plus 2.
01:28
So in the top, the 3x minus 3 cancels.
01:31
We left with 5x.
01:33
In the bottom, 2x cancels and we're left with 5...