SOLUTION: For the function f(x)=x^2 -12, find (f o f^-1)(4) the answear is a.6 b.4 c.0 D 10. Im keep getting 10,i dunno ot right can u please help me thank u.

Algebra ->  Functions -> SOLUTION: For the function f(x)=x^2 -12, find (f o f^-1)(4) the answear is a.6 b.4 c.0 D 10. Im keep getting 10,i dunno ot right can u please help me thank u.      Log On


   

Question 1017508: For the function f(x)=x^2 -12, find (f o f^-1)(4) the answear is a.6 b.4 c.0 D 10. Im keep getting 10,i dunno ot right can u please help me thank u.
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
.
f%28x%29=y=x%5E2-12
f%5E%28-1%29: x=y%5E2-12
y%5E2=x%2B12
y=sqrt%28x%2B12%29
.
For x=4:
y=sqrt%284%2B12%29=sqrt%2816%29=4
.
Since f%5E%28-1%29=4, (f+o f%5E%28-1%29)=f%284%29
.
f%284%29=4%5E2-12=16-12=4
.