Question:
Show that $x=-2$ is a solution of $3 x^{2}+13 x+14=0$.
Solution:
Given that the equation $3 x^{2}+13 x+14=0$
$3 x^{2}+7 x+6 x+14=0$
$x(3 x+7)+2(3 x+7)=0$
$(3 x+7)(x+2)=0$
$(3 x+7)=0$
$x=\frac{-7}{3}$
$x=\frac{-7}{3}$
or
$(x+2)=0$
$x=-2$
Therefore, $x=-2$ is the solution of given equation.
Hence, proved.