Answer:
f(f(x)) = 27[tex]x^{4}[/tex] + 18x² + 4
Step-by-step explanation:
To find f(f(x)) substitute x = f(x) into f(x) , that is
f(3x² + 1)
= 3(3x² + 1)² + 1 ← expand parenthesis using FOIL
= 3(9[tex]x^{4}[/tex] + 6x² + 1) + 1 ← distribute parenthesis by 3
= 27[tex]x^{4}[/tex] + 18x² + 3 + 1 ← collect like terms
= 27[tex]x^{4}[/tex] + 18x² + 4
Hello,
[tex](fof)(x)=f(f(x))\\\\=3(3x^2+1)^2+1\\\\=3(9x^4+6x^2+1)+1\\\\\boxed{=27x^4+18x^2+4}[/tex]
