Question

f(x)=7x+7 and g(x)=6x^2
find (fg)(x)

Answer 1

f(x) = 7x + 7; g(x) = 6x²

(fg)(x) = f(x) · g(x)

(fg)(x) = (7x + 7) · 6x² = (7x)(6x²) + (7)(6x²) = 42x³ + 42x²

Answer 2

$F(g(x))=7(6x^2)+7$ \\ We plug in our g(x) equation into f(x)
$F(g(x)) = 42x^2+7=0 \\ F(g(x)) = x^2=-1/6 \\ F(g(x)) = x = \sqrt \frac{-1}{6}i$