Question

f:R—>R, f(x)=x²-x-2. Find fof.

Answer 1

$f(x) = {x}^{2} - x - 2 \\ fof = f(f(x)) \\ = {( {x}^{2} - x - 2)}^{2} - ( {x}^{2} - x - 2) - 2 \\ = ({x}^{4} + {x}^{2} + 4 - 2 {x}^{3} - 4 {x}^{2} + 4x)- ( {x}^{2} - x - 2) - 2 \\ = {x}^{4} - 2 {x}^{3} - 4 {x}^{2} + 5x + 4$