f(x) = √x^2+12x+36 and g(x) = x^3-12

Question

Which expression is equal to f(x • g(x)?

x^4-6x^3-12x+72

x^4-12^3+6x-72

x^4+6x^3-12x-72

7x^3-12x-72

Answer 1

There is a right parenthesis is missing. Is it f(xg(x)) or f(x)g(x)?

 

If you mean f(x)• g(x), then

 

f(x)=√(x²+12x+36)=√(x+6)²=|x+6|

 

f(x)• g(x)=(x+6)(x³-12)=x⁴+6x³-12x-72, if x>-6.

f(x)• g(x)=-(x+6)(x3-12)=-x⁴-6x³+12x+72, if x<-6.