# Break line within array or eqnarray

I have used the following codes to generate two equations. However, the second equation overlaps with the equation index. Can someone please help me look it pretty by breaking the 2nd equation into two lines? By the way, I also read on stackexchange to avoid eqnarray and instead use "array". Could you help me with that too? Apparently, using these codes within array resulted in error.

\begin{eqnarray}
\lambda_{R,t} &=& \dfrac{(C_{R,t}-\phi_c C_{R,t-1})^{-\sigma}}
{P_t(1+\tau_t^c)} - \phi_c \beta \dfrac{(E_t C_{R,t+1}-\phi_c C_{R,t})^{-
\sigma}}{P_t(1+\tau_t^c)} \\
Q_t &=& \beta E_t{(1-\delta)Q_{t+1} + \lambda_{R,t+1}R_{t+1}U_{t+1}(1-
\tau^k_{t+1})} - \lambda_{R,t+1}P_{t+1} \left[\Psi_1(U_t-1) + \dfrac{\Psi_2}
{2}(U_t-1)^2 \right]
\end{eqnarray}


The environment align is probably the way to go here:

\documentclass[12pt]{article}
\usepackage{amsmath}

\begin{document}

\begin{align}
\lambda_{R,t} &= \dfrac{(C_{R,t}-\phi_c C_{R,t-1})^{-\sigma}}
{P_t(1+\tau_t^c)} - \phi_c \beta \dfrac{(E_t C_{R,t+1}-\phi_c C_{R,t})^{-
\sigma}}{P_t(1+\tau_t^c)} \\
Q_t &= \beta E_t{(1-\delta)Q_{t+1} + \lambda_{R,t+1}R_{t+1}U_{t+1}(1-
\tau^k_{t+1})} \\
& - \lambda_{R,t+1}P_{t+1} \left[\Psi_1(U_t-1) + \dfrac{\Psi_2}
{2}(U_t-1)^2 \right] \nonumber
\end{align}

\end{document}


You also have to use \nonumber in order to avoid having three equation numbers.

Hope that helps.

Romain

• awesome! Exactly how I wanted it. Thank you Romain.
– TRa
May 21, 2018 at 10:29

Another suggestion, with the aligned environment. You should not use eqnarrayas it leads to bad spacing around the alignment points.

\documentclass[12pt]{article}
\usepackage{mathtools}

\begin{document}

\begin{align}
\lambda_{R,t} &= \dfrac{(C_{R,t}-\phi_c C_{R,t-1})^{-\sigma}}
{P_t(1+\tau_t^c)} - \phi_c \beta \dfrac{(E_t C_{R,t+1}-\phi_c C_{R,t})^{-
\sigma}}{P_t(1+\tau_t^c)} \\[1ex]
Q_t &=\raisetag{3.7ex} \begin{aligned}[t]
\beta E_t{(1-\delta)Q_{t+1} + \lambda_{R,t+1}R_{t+1}U_{t+1}(1-
\tau^k_{t+1})} & \hspace*{5cm}\\
- \lambda_{R,t+1}P_{t+1} \Bigl[\Psi_1(U_t-1) + \dfrac{\Psi_2}
{2}(U_t-1)^2 \Bigr]
\end{aligned}
\end{align}

\end{document}


You can use split inside align (never use eqnarray)

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{align}
\lambda_{R,t} &=
\frac{(C_{R,t}-\phi_c C_{R,t-1})^{-\sigma}}{P_t(1+\tau_t^c)}
- \phi_c \beta \frac{(E_t C_{R,t+1}-\phi_c C_{R,t})^{-\sigma}}{P_t(1+\tau_t^c)}
\\[1ex]
\begin{split}
Q_t &=
\beta E_t{(1-\delta)Q_{t+1} + \lambda_{R,t+1}R_{t+1}U_{t+1}(1-\tau^k_{t+1})}
\\

I used \Bigl and \Bigr because the size chosen by \left and\rightseems too large for this formula. The[1ex]` helps in distinguishing between the two formulas.