Question

Let f(x) = 5x + 12. Find f-1(x) (HELP,MEDAL REQUIRED)

Answer 1

I'm assuming you want the inverse. The way I think about it is kind of like doing everything backwards in backwards order. So since the first thing being done to x is multiplying by 5 and THEN 12 is being added, to get the inverse we first subtract 12 and then divide by 5. Get it? Doing everything backwards in backwards order.

Alternatively, you could switch the f(x) with x and the x with f(x) and solve. So you would have\[x = 5f(x) + 12\]And then you would solve for f(x). Either way, you should get\[f^{-1}(x) = \frac{ x-12 }{ 5 }\]

Answer 2

Makes sense?

Answer 3

yes thank you!