Question

If f(x) = 5x, what is f–1(x)?

Answer 1

When you are finding an inverse of a function, you switch the x and the y and solve for the new y.  Our y = 5x, when switching x and y will be x = 5y.  Now we have to find the new y.  Dividing both sides by 5 we get $y= \frac{1}{5} x$.  The really cool thing about functions that are inverses of each other is that their coordinates, (x, y) are switched to.  If a point (1, 2) is on f(x), the point (2, 1) is on the inverse. And they always reflect through the line y = x.  Just a bit of info.