# Linebreaking gather (equation) environment?

Please help me to line break this gather environment. You can clearly see which line I want broken by where I've placed the split environment in my code. It's too long for 1 line.

I also want it tagged (i.e. $(20)$ or $(21)$ or whatever on the right). I'm using gather because I want all the equations to be aligned together by the LHS margin.

I use LaTeX.

\documentclass{article}
\usepackage[fleqn]{amsmath}

\begin{document}

\begin{gather}
Q(CSAD_t(\tau)|\mathbf{Z}) = \alpha(\tau) + \beta(\tau)|R_{M,t}| + \gamma(\tau)R_{M,t}^2 + \epsilon_t \\
\begin{split}
Q(CSAD_t(\tau)|\mathbf{Z}) &= \alpha(\tau) + \beta(\tau)_0|R_{M,t}| + \gamma(\tau)_0R_{M,t}^2 + \beta(\tau)_1D_{ALL,t}|R_{M,t}| \\
&+ \gamma(\tau)_1D_{ALL,t}R_{M,t}^2 + \epsilon_t \\
\end{split} \newline
Q(CSAD_t(\tau)|\mathbf{Z}) = \alpha(\tau) + \mathbf{\beta(\tau)}\mathbf{D}'|R_{M,t}| + \mathbf{\gamma(\tau)}\mathbf{D}'R_{M,t}^2 + \epsilon_t \\
\mathbf{\beta(\tau)} = [\beta(\tau)_0, \beta(\tau)_1,...,\beta(\tau)_6];\textrm{   }\mathbf{\gamma(\tau)} = [\gamma(\tau)_0,\gamma(\tau)_1,...,\gamma(\tau)_6];\textrm{   }\mathbf{D} = [1, D_{1,t},...,D_{6,t}] \notag \\
\tau = 0.05,0.1,0.5,0.9,0.95 \notag
\end{gather}

\end{document}
-

You can get the numbers by setting the equation counter to one less than the first number you want, in this case 19. You had a glitch after the {split} because you used \newline, which is a text and not a math command. Don't mix the two! I put in \\ instead, and a \notag to suppress the number that would be there (going by your example). Finally, I replaced your explicit spacing in the last few lines with an {aligned} subenvironment, which allows me to get the final equations lined up as well as automatically spread out.

\documentclass{article}
\usepackage[fleqn]{amsmath}

\begin{document}

\setcounter{equation}{19}
\begin{gather}
= \alpha(\tau) + \beta(\tau)|R_{M,t}| + \gamma(\tau)R_{M,t}^2 + \epsilon_t \\
\begin{aligned}
&= \alpha(\tau) + \beta(\tau)_0|R_{M,t}| + \gamma(\tau)_0R_{M,t}^2 \\
&+ \beta(\tau)_1D_{ALL,t}|R_{M,t}| + \gamma(\tau)_1D_{ALL,t}R_{M,t}^2 + \epsilon_t
\end{aligned} \notag\\