Let $M = (X, \mathcal{F}, \mu)$ be a D1158: Measure space such that

(i)	\begin{equation} \mu(X) < \infty \end{equation}
(ii)	$f : X \to \mathbb{C}$ is a D5148: Borel-measurable complex function on $M$
(iii)	$1 \leq q < p \leq \infty$
(iv)	\begin{equation} \left( \int_X |f|^p \, d \mu \right)^{1/p} < \infty \end{equation}

Then \begin{equation} \left( \int_X |f|^q \, d \mu \right)^{1/q} < \infty \end{equation}