Question

For what values of k will the pair of equations $x+2y+7=0$ and $2x+ky+14=0$ represent coincident lines?

• A. 3
• B. 6
• C. 4
• D. 9

Answer 1

The correct option is C 4

Given system of equations $x+2y+7=0$ and $2x+ky+14=0$. We know two equations will have coincident lines when,
$\frac{a_1}{a_2}=\frac{b_1}{b_2}=\frac{c_1}{c_2}$
As these equations form coincident lines, $\frac{1}{2}=\frac{2}{k}$. Cross multifling, we get $k=4$.