00:01
Okay, if the investigator charges $500 plus $80 per hour, then we know that our equation is going to be f of x equals 500 plus 80x.
00:10
In other words, if you think of it like frozen yogurt, we've got the base rate and then we've got a rate per hour per x.
00:16
Okay, inverse function.
00:18
If f of x is 500 plus 80x, this means that y equals 500 plus 80x.
00:26
Okay, we can rewrite this as interchanging x and y, x equals 500 plus 80y.
00:40
This means that 80y equals x minus 500, so y equals 1 over 80 x minus 500.
00:51
So y equals 1 over 80 x minus 500 over 80.
00:56
In other words, the inverse function of x equals 1 over 80x minus what's 500 divided by 80? 50 over 8 simplifies to 25 over 4.
01:15
1 over 80 x minus 25 over 4...