f-1(4) when f(x) = 3x minus 4, all over 5

can anyone tell me what subject is this? im in algebra 2. if anyone can help me solve it, it would be better. thank you!

Question

f-1(4) when f(x) = 3x minus 4, all over 5

can anyone tell me what subject is this? im in algebra 2. if anyone can help me solve it, it would be better. thank you!

anonymous · Answer

Could you draw the equation? I'm a bit confused as to what you're trying to show with your equation.

anonymous · Answer

sure

anonymous · Answer

f^-1(4) when f(x) = $$\frac{ 3x-4 }{ 5 }$$

anonymous · Answer

Ah, f(x)  to the power of -1(4).

anonymous · Answer

$$f ^{-1} (4)$$

anonymous · Answer

yes i think so

anonymous · Answer

That represents an inverse equation, if I remember correctly.

anonymous · Answer

So, switch around y and x, solve for y, then plug in 4.

anonymous · Answer

i know but i can't think of what lesson or subject it was, i got a test and im trying to review

anonymous · Answer

Oh. Lemme grab my pre-calc book from the closet. One second.

anonymous · Answer

so $$x = \frac{ 3y-4 }{ 5}$$

anonymous · Answer

ok thank you!

anonymous · Answer

Well, in my book it's under the 'Transformations of Functions' section.

anonymous · Answer

And yup, that would be it; you just have to manipulate it to isolate y then you have your answer.

anonymous · Answer

so i switch around y and x and plug in -4 for y? or for x?

anonymous · Answer

im working on it on my paper as well

anonymous · Answer

Once you've moved around y and x, you'd plug in 4 for x. It is 4, right, not negative 4? Or did you write it wrong above?

anonymous · Answer

nono its f-1(4)but since is finding the inverse, i thought it would be -4 because of 4

anonymous · Answer

so i got this...

anonymous · Answer

y=8 am i right?

anonymous · Answer

Gimme a sec I'll do the math.

anonymous · Answer

yup, y=8

anonymous · Answer

thank you very much!!!

anonymous · Answer

No problem. :)