111. Reduce the equations of the lines to normal form:
1) $2 x-3 y-10=0$
2) $3 x+4 y=0$
Solution. In the first equation, $C=-10$, therefore, the normalizing factor $M$ should be taken with a positive sign:

$$
M=\frac{1}{\sqrt{2^{2}+3^{2}}}=\frac{1}{\sqrt{13}} .
$$

Multiplying all terms of the equation by this factor, we obtain the equation of the line in normal form:

$$
\frac{2}{\sqrt{13}} x-\frac{3}{\sqrt{13}} y-\frac{10}{\sqrt{13}}=0
$$

In the second equation, $C=0$, therefore, the normalizing factor can be taken with either sign, for example, with a positive sign:

$$
M=\frac{1}{\sqrt{3^{2}+4^{2}}}=\frac{1}{5}
$$

Multiplying all terms of the given equation by this factor, we obtain the equation in normal form:

$$
\frac{3}{5} x+\frac{4}{5} y=0
$$