Question

For what value of $k$, the following system of equation will represent the coincident lines?
$x+2y+7=0$
$2x+ky+14=0$

Answer 1

Lines are coincident $\Rightarrow$ The ratio of respective coefficients must be equal.

$\Rightarrow \frac{1}{2}=\frac{2}{k}=\frac{7}{14}$

$\Rightarrow k=4$