Question:
If the system of equations kx − 5y = 2, 6x + 2y = 7 has no solution, then k =
(a) $-10$
(b) $-5$
(c) $-6$
(d) $-15$
Solution:
The given systems of equations are
$k x-5 y=2$
$6 x+2 y=7$
If $\frac{a_{1}}{a_{2}}=\frac{b_{1}}{b_{2}} \neq \frac{c_{1}}{c_{2}}$
Here $a_{1}=k, a_{2}=6, b_{1}=-5, b_{2}=2$
$\frac{k}{6}=\frac{-5}{2}$
$k=\frac{-30}{2}$
$k=-15$
Hence, the correct choice is $d$.