SOLUTION: If {{{g(x)=x^2+4x}}} find {{{g^-1(5)}}} I know you need to solve for x but I can't remember how. {{{y=x^2+4x}}} {{{y=x(x+4)}}} {{{y/(x+4) = x}}} but I still have

Question 125918This question is from textbook Elementary Functions
: If find
I know you need to solve for x but I can't remember how.

but I still have an x with the y??
Please help. I know the solution should be x = some equation where the equation cannot also have an x in it.
thank you This question is from textbook Elementary Functions

Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!

What you have is a relation between
2 variables. You can't "solve" any more
than you did when you got
If I say , then there is a
corresponding value for , but normally
depends on whatever is.
You can find the roots of
by setting . You can see in
than and
will make
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