関連ワード:  why does a function have an inverse    why can a function have an inverse    why does a function not have an inverse    why does a function have no inverse    why does a quadratic function not have an inverse    why does a function need to be surjective to have an inverse    does a quadratic function have an inverse    does a cubic function have an inverse    does a constant function have an inverse    does a bijective function have an inverse