Answer
$(f \circ f)(x) = x^4-4x^2+2$
Work Step by Step
Functions involved:
$f(x)=x^2-2$
Substitute $f(x)$ into $f(x)$:
$(f \circ f)(x) = (x^2-2)^2-2$
Expand:
$(f \circ f)(x) = x^4-4x^2+4-2$
Simplify:
$(f \circ f)(x) = x^4-4x^2+2$