mathURL
http://mathurl.com/ybuujhlf
<img src="http://mathurl.com/ybuujhlf.png" />
![\small
C_1 \, C_2
\left[ \, R_1 \, R_2 + R_0 \left( R_1 + R_2 \right) \, \right]](http://mathurl.com/ybuujhlf.png)