\footnotesize.
Code: Select all
\documentclass[12pt, leqno]{article}
\begin{document}
\footnotesize
\begin{equation}
\frac{\partial Ln(P_{t} )}{\partial \hat{r}}=-\frac{(1-\varphi)[1-\theta-\frac{(\hat{g}+\pi)(1-\theta)(1-\delta)}{\hat{\rho}(\hat{r} )+(1-\varphi)\pi+\delta)}]+\hat{\rho}'(\hat{r})[\theta+\frac{(\hat{g}+\pi)(1-\theta)(1-\delta)((1-\varphi)(\hat{r}+\pi)+\delta)}{(\hat{\rho}(\hat{r} )+(1-\varphi)\pi+\delta)^{2}} ]}{\theta\hat{\rho}(\hat{r} )-\varphi\pi+(1-\theta)(1-\varphi) \hat{r}-\hat{g}+\tau+(\hat{g}+\pi)(1-\theta)(1-\delta)\frac{\hat{\rho}(\hat{r})-(1-\varphi) \hat{r}}{\hat{\rho}(\hat{r} )+(1-\varphi)\pi+\delta)}}.
\end{equation}
\normalsize
\end{document}
