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

Let L=3x+4y-8=0 and

$\begin{array}{l}A\left(2,-5\right)=\left(x_1,y_1\right)B\left(-5,2\right)=\left(x_2,y_2\right)\\ L_{11}=3\left(2\right)+4\left(-5\right)-8=6-70-8=-22\\ L_{22}=3\left(-5\right)+4\left(2\right)-8=-15+8-8=-15\\ L_{11}.L_{22}=\left(-22\right)\left(-15\right)=330>0\\ \therefore L_{11}.L_{22}>0\end{array}$

$\therefore$ The points lies on same side of L