$$\frac{t}{r^{2}-2s}-\frac{1}{r^{2}-10t+2s}$$
$\frac{tr^{2}-10t^{2}+2s+2st-r^{2}}{\left(r^{2}-2s\right)\left(r^{2}+2s-10t\right)}$
$\frac{r^{4}-10r^{2}+4s^{2}+4sr^{2}-40st+20s+100t^{2}-20tr^{2}}{\left(r^{2}-2s\right)\left(r^{2}+2s-10t\right)^{2}}$
