Precalculus — Functions

Inverse functions

continues from lesson 3 — values defined earlier in the course stay live here

An inverse undoes: if f sends 4 → 4, then f⁻¹ sends 4 → 4 back. Only one-to-one functions have inverses — that's why we restrict x ≥ 0 before inverting x²:

sq\left(x\right) = x^{2}

restricted to x ≥ 0

sq_{inv}\left(y\right) = \sqrt{y}

its inverse

✓ pass

\mathrm{abs}\left(\mathrm{sq_{inv}}\left(\mathrm{sq}\left(7\right)\right) - 7\right) < 10^{-9}

undo really undoes