One diagonal of a square is3x-4y + 8 = 0 and one vertex is (-l , 1). Then the area of square is 

$\text{ Distance of vertex from diagonal }=\left|\frac{-3-4+8}{5}\right|=\frac{1}{5}$

$\text{ So, length of diagonal is }\frac{2}{5}\text{ . }$

$\therefore \text{ Area of square }=\frac{1}{2}\times \frac{2}{5}\times \frac{2}{5}=\frac{2}{25}\text{ sq. unit }$