Latex:  
&amp;f_t \left|_{~_{f=f_0, R=R_{tot}}} \right. ~\rightarrow~ f_0 = \dfrac{R_{IN} + R_L + R_{tot}}{2 \pi C R_L (R_{IN} + R_{tot})}  \\\\
                &amp;f_t \left|_{~_{f=f_1, R=0}}\right. ~\rightarrow~ f_1 = \dfrac{R_{IN} + R_L + R_{tot}}{2 \pi C R_{IN} (R_L + R_{tot})}
