# Multi-line equation inside itemize

I'm creating a homework for college students and I have five expressions that I need to itemize. Here's a MWE.

\documentclass[letterpaper,12pt]{article}
\usepackage{amsmath,amssymb,enumitem}

% Negation symbol consistent with textbook:
\newcommand{\shortsim}{\raise.17ex\hbox{$\scriptstyle \sim$}}
\renewcommand{\neg}{\shortsim}

\begin{document}

\begin{enumerate}[label=\alph*)] \large
\item $(\exists n \in \mathbb{N})[Prime(n) \wedge Even(n)]$

\item $(\neg \forall n_1 \in \mathbb{Z}) (\exists n_2 \in \mathbb{Z})[n_1 > n_2]$
\item $(\neg \forall n \in \mathbb{Z})[Divides(4, n) \Rightarrow Even(n)]$
\item $(\neg \forall n \in \mathbb{Z})[(Divides(15, n) \Rightarrow \big ( Divides(3, n) \wedge Divides(5, n) \big )]$
\item \begin{multline*} (\neg \forall x \in \mathbb{N})(\forall y \in \mathbb{N})\bigg [Coprime(x,
y) \Leftrightarrow \bigg( (\nexists k \in \mathbb{N} )[(1 < k <x ) \land \\ \qquad \qquad \qquad (1 < k < y) \land Divides(k, x) \land (Divides(k, y))]  \bigg) \bigg ]
\end{multline*}
\end{enumerate}

\end{document}


The result is that the final equation is hanging below the (e):

What can I do here, if anything? If enumerate is not an appropriate environment, please advise.

You can use aligned within math mode and decide where align the lines by &.

Also, I changed a little the size of delimiters and used operator font for Coprime and others.

\documentclass[letterpaper,12pt]{article}
\usepackage{amsmath,amssymb,enumitem}

\begin{document}

\begin{enumerate}[label=\alph*)] \large
\item $(\exists n \in \mathbb{N})[Prime(n) \wedge Even(n)]$
\item $(\neg \forall n_1 \in \mathbb{Z}) (\exists n_2 \in \mathbb{Z})[n_1 > n_2]$
\item $(\neg \forall n \in \mathbb{Z})[Divides(4, n) \Rightarrow Even(n)]$
\item $(\neg \forall n \in \mathbb{Z})[(Divides(15, n) \Rightarrow \big ( Divides(3, n) \wedge Divides(5, n) \big )]$
\item \begin{aligned}[t] (\neg \forall x \in \mathbb{N}) (\forall y \in \mathbb{N}) \Bigl[ \operatorname{Coprime}(x,y) \Leftrightarrow \bigl( (\nexists k \in \mathbb{N} )[(1 < k <x ) \\ \land (1 < k < y) \land \operatorname{Divides}(k, x) \land (\operatorname{Divides}(k, y))] \bigr) \Bigr] \end{aligned}
\end{enumerate}

\end{document}


Or you could just use inline equations. If you really want to use words for divides etc., then you may want to use math operators or something like this. Personally I would use the symbols for those.

\documentclass[letterpaper,12pt]{article}
\usepackage{amsmath,amssymb,enumitem}
\DeclareMathOperator{\Prime}{Prime}
\DeclareMathOperator{\Even}{Even}
\DeclareMathOperator{\Divides}{Divides}
\DeclareMathOperator{\Coprime}{Coprime}
\begin{document}

\begin{enumerate}[label=\alph*)] \large
\item $(\exists n \in \mathbb{N})[\Prime(n) \wedge \Even(n)]$
\item $(\neg \forall n_1 \in \mathbb{Z}) (\exists n_2 \in \mathbb{Z})[n_1 > n_2]$
\item $(\neg \forall n \in \mathbb{Z})[\Divides(4, n) \Rightarrow \Even(n)]$
\item $(\neg \forall n \in \mathbb{Z})[(\Divides(15, n) \Rightarrow \big ( \Divides(3, n) \wedge \Divides(5, n) \big )]$
\item $(\neg \forall x \in \mathbb{N})(\forall y \in \mathbb{N})\bigg [\Coprime(x, y) \Leftrightarrow \bigg( (\nexists k \in \mathbb{N} )[(1 < k <x )\land (1 < k < y) \land \Divides(k, x) \land (\Divides(k, y))] \bigg) \bigg ]$
\end{enumerate}

\end{document}


• Yes, I prefer the symbols as well but this is as part of a course where they have not yet been introduced to the divides" symbol ($\mid$) so I just introduce it as a predicate instead. @Sigur's response allowed me the extra space, so I went with that. Thanks for the help. – Jason Sep 17 '18 at 16:32