If the line  $3x+4y=8$ is denoted by $L$, then the points $(2,-5),(-5,2)$

$\begin{array}{l}{L}_{11}=3\left(2\right)+4(-5)-8<0\\ L_{22}=3(-5)+4\left(2\right)-8<0\end{array}$

Since  $L_{11}\text{\hspace{0.17em}and\hspace{0.17em}}{L}_{22}$ have the same sign, given points lie on the same side of  $L=0$.