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Mathematics 8 Online
OpenStudy (rosepetalingg):

Find the inverse of this function

OpenStudy (rosepetalingg):

can someone explain how to do this?

OpenStudy (rosepetalingg):

@Lowkey.S @Loli @babygirl4556

OpenStudy (rosepetalingg):

@imqwerty @zepdrix @.Sam. @Awolflover1

OpenStudy (eliesaab):

You have to solve the equation \[y=\sqrt[3]{x-2}+8 \] for x in terms of y

OpenStudy (rosepetalingg):

okay so what would be my first step after that? do I get rid of the square root? I am really having trouble

OpenStudy (rosepetalingg):

@eliesaab

OpenStudy (eliesaab):

\[y-8=\sqrt[3]{x-2} \]

OpenStudy (eliesaab):

Cube both sides

OpenStudy (rosepetalingg):

\[y^3-8^3=x-2\]

OpenStudy (eliesaab):

\[ (y-8)^3=x-2 \]

OpenStudy (rosepetalingg):

is that right..? lol

OpenStudy (eliesaab):

No

OpenStudy (rosepetalingg):

okay and then where do you go next from that?

OpenStudy (eliesaab):

\[ y^3-24 y^2+192 y-512=x-2 \]

OpenStudy (rosepetalingg):

okay but how did you get there?

OpenStudy (eliesaab):

Use the formula \[ (a-b)^3=a^3-3 a^2 b+3 a b^2-b^3 \]

OpenStudy (rosepetalingg):

okay and then after that do you just add the 2 to the other side to solve for x?

OpenStudy (eliesaab):

Yes

OpenStudy (rosepetalingg):

and then after that do you do anything else?

OpenStudy (eliesaab):

replace y by x to get the inverse function is \[ g(x)=x^3-24 x^2+192 x-510 \]

OpenStudy (rosepetalingg):

thats not one of my answer choices :(

OpenStudy (eliesaab):

What are your answer choices?

OpenStudy (eliesaab):

It could be the same thing since here we expanded

OpenStudy (rosepetalingg):

f-1(x)=(x-8)^3+2 f-1(x)=(x+8)^3+2

OpenStudy (rosepetalingg):

i have two more let me type them

OpenStudy (eliesaab):

\[ (x-8)^3+2 \]

OpenStudy (rosepetalingg):

\[f^-1(x)=\sqrt[3]{x-8} +2\]

OpenStudy (eliesaab):

That is the same thing that I gave you where we expanded \((x-8)^3\)

OpenStudy (eliesaab):

The answer is \[ (x-8)^3 +2\]

OpenStudy (rosepetalingg):

okay thanks for your help

OpenStudy (eliesaab):

You are very welcome

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