Question

Which equation is the inverse of y = x2 + 16?
y = x2 – 16
y = plus-or-minus StartRoot x EndRoot minus 16
y = plus-or-minus StartRoot x minus 16 EndRoot
y = x2 – 4

Answer 1

Swap x and y and solve: x = y^2 + 16 → y^2 = x − 16 → y = ±√(x − 16).

So the correct choice is: y = ±√(x − 16). (Note: for a single-valued inverse you must restrict the original domain, e.g. x ≥ 0 gives y = +√(x − 16).)