75. Write the equation of a line parallel to the $O x$ axis and cutting off a segment equal to -2 from the $O y$ axis. Check if the points $A(2; -2)$ and $B(3; 2)$ lie on this line.
Solution. According to the problem, the slope $k=0$, the initial ordinate $b=-2$, therefore, the equation of the line we are looking for is $y=-2$. It is easy to see that the coordinates of any point $M(x; -2)$ satisfy this equation.

Point $A$ lies on the line we are looking for, since its coordinates satisfy the equation of the line $y=-2$. Point $B$ does not lie on the line, since its coordinates do not satisfy the equation of the line $y=-2$ (Fig. 14).