Let f(x) = 5x + 12. Find f-1(x).

Question

anonymous · Answer

@johnweldon1993 WHAT I know this is different but WHAT

johnweldon1993 · Answer

lol yeah this one is COMPLETELY different...it's an inverse! similar looking right?

f(-1) = plug in -1 for 'x'
and
f-1(x) = inverse equation

So what you do...

y = 5x + 12

You switch the 'x' and the 'y'

x = 5y + 12

And now you use algebra to solve for 'y' again

anonymous · Answer

Yep you lost me which one do I use

johnweldon1993 · Answer

lol f-1(x) here...the inverse...

so

your equation is

y = 5x + 12      (Note how I replaced f(x) with y ...same thing)

What you do to solve an inverse equation *f-1(x)* is you switch the position of the 'x' and the 'y' in the equation...

x = 5y + 12

Now you need to solve for 'y' again...

x = 5y + 12

Lets subtract 12 from both sides

x - 12 = 5y

And then divide everything by 5

$$\large y  = \frac{x - 12}{5}$$

and that would be your answer...does that make sense?

anonymous · Answer

After looking at it a few times I think so... ahah. There's a couple others I will try on my own right now.

johnweldon1993 · Answer

If you need help feel free to message me :)