Question

Please help i have no idea how to do this:

Find the inverse of the function.

f(x) = 3sqrt(x/9)- 4

Answer 1

You switch your 'x' and 'y' and solve for 'y' again

Answer 2

To solve for inverse, change the x into y and y into x and then solve for y!

Answer 3

\[y = 3\sqrt{\frac{ x }{ 9 }} - 4\]

switch the 'x' and 'y'

\[x = 3\sqrt{\frac{ y }{ 9 }} - 4\]

how would you solve for 'y' again?

Answer 4

i dont know how to do that with the cubed root though :/

Answer 5

Oh that's a cubed root? oh sorry...let me do that again lol

Answer 6

\[x = \sqrt[3]{\frac{ y }{ 9 }} - 4\]

Answer 7

well i know you add four to both sides right? but im not sure how to continue

Answer 8

Well....you want to get 'y' by itself...so first add 4 to both sides.....what do you have on the left side now?

Answer 9

nvm lol you beat me to that part haha

Answer 10

:)

Answer 11

Well you want to get rid of that radical....to get rid of a SQUARE root....you raise both sides to the 2nd power....

so to get rid of a CUBED root....you raise both sides to the 3rd power right?

Answer 12

oh ok! so youd have 64=y/9, then y=64/9 or 7.11?

Answer 13

just kidding

Answer 14

You forgot your 'x'

On the left side ....lol nvm continue :D

Answer 15

hah sorry i forgot about the x
yeah. ok.. so 64x= y/9? then y=64x/9?

Answer 16

Not quite

on the left side before you cubed both sides you have

x + 4 right?

so when you cube both sides you get

(x + 4)^3 = y/9

then you would multiply both sides by 9 and get.....?

Answer 17

oh yeah ok hang on a sec

Answer 18

so (x^3+12x^2+48x+64)/9=y

Answer 19

oh i think the answer is just 9(x+4)^3, sorry i kept messing up. i think i got it now.

Answer 20

lol there you go :) don't simplify unless you really have to :)

Answer 21

thanks youre the best!

Answer 22

anytime :)