Let f(x) = 5x + 12. Find f^-1(x).
I got x-2/5
x minus 2 over the quantity 5.

Question

Let f(x) = 5x + 12. Find f^-1(x).
I got x-2/5
x minus 2 over the quantity 5.

misty1212 · Answer

HI!!

anonymous · Answer

Hello. o:

misty1212 · Answer

function says ''multiply by 5, add 12"

misty1212 · Answer

inverse says
"subtract 12, divide by 5"

anonymous · Answer

Supposed to do the inverse, so I did. Lemme screenshot.

misty1212 · Answer

you wrote $$\frac{x-2}{5}$$ but i bet you meant $$\frac{x-12}{5}$$  since there is not 2 in it

misty1212 · Answer

no i got it
you got it too i think

anonymous · Answer

Yeah I got that. xD I forgot the 1 to make it 12. Here's le work. http://prntscr.com/8ysskd

anonymous · Answer

I wrote two and from there I thought it was, derp. xD

misty1212 · Answer

man is that a bad mistake (not yours, the screen shot)

misty1212 · Answer

where did that come from?

anonymous · Answer

I used a program called lightshot to take screenshots. Helpful little thing, really.

misty1212 · Answer

lol no dear i dont mean the screenshot itself
i mean who wrote it?

misty1212 · Answer

does it come from a text? your teacher? on line system?

anonymous · Answer

Oh, someone on Brainly. I wrote the same thing, oh wow that's the wrong screenshot. XD That was for another question I worked out. I like making sure I do everything perfectly because math is my weakpoint. When I come here it's to make sure I understand everything to its fullest. Right now functions are my weakest point, but I work them out on my own then come here to see if I'm right.

anonymous · Answer

Most people come here for answers, I rather be taught so I can do it on my own. I can't trust any answers I find on the web, they may be wrong, so if I learn it by someone here, then woohoo, I can make sure I got it down pat.

misty1212 · Answer

ok i don't mean to be critical but there is a huge mistake there

anonymous · Answer

Where?
The screenshot?

misty1212 · Answer

$$f(x)=x^2-81$$ is not a one to one function
it is a parabola and doesn't pass the horizontal line test 
for example $$f(10)=-19=f(-10)$$

anonymous · Answer

I got $$\frac{ x-12 }{ 5 }$$

misty1212 · Answer

when you solve you should get $$\pm\sqrt{x+81}$$

misty1212 · Answer

yeah that is right, i am talking about the screen shot

anonymous · Answer

That's what I got. It should have two answers because of the square root thing so the = and - are there. Where's the mistake?

anonymous · Answer

+ and -*

misty1212 · Answer

i didn't see it in the screen shot is all

anonymous · Answer

Ah. Thanks!

misty1212 · Answer

$$\color\magenta\heartsuit$$