Question:
The solution of the equation ax + b = 0 is
(a) $x=\frac{a}{b}$
(b) $x=-b$
(c) $x=\frac{-b}{a}$
(d) $x=\frac{b}{a}$
Solution:
(c) Given equation is $a x+b=0$
$\Rightarrow$ $a x=-b \quad$ [transposing $b$ to RHS]
$\Rightarrow$ $\frac{a x}{a}=\frac{-b}{a}$ [dividing both sides by a]
$\therefore$ $x=\frac{-b}{a}$
Hence, the solution of the equation $a x+b=0$ is $x=-\frac{b}{a}$.