Question

whats x in 2=ln(x+9)

Answer 1

symmetrical across x=0 (this is true for all functions that contain only even powers of x).

domain:
x^2-9>0
x^2>9
{x|x<-3 or x>3}

zeros:
ln(x^2-9)=0=ln(1)
x^2-9=1
x^2=10
x=+sqrt10 or -sqrt10

inverse function:
y=ln(x^2-9)
e^y=x^2-9
x^2=e^y+9
x=+-sqrt(e^y+9)
so we get a group of functions because f(x) is not injective
one obvious possible function is f^-1(x)=sqrt(e^y+9)
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Answer 2

what is the x?

Answer 3

meant f sorry