Question

The value of $k$ for which the pair of linear equation $9x+15-2=0$ and $3x+ky+5=0$. represents parallel lines is:

• A. $k=5$
• B. $k=-5$
• C. $k=3$
• D. $k=-3$

Answer 1

Answer: (A)

$k=5$

For two parallel lines we have,

$\frac{a_1}{a_2}=\frac{b_1}{b_2}\ne \frac{c_1}{c_2}$

Given equations are $9x+15-2=0$ and $3x+ky+5=0$

Compare these equations with standard equations:

$a_{1}x+b_{1}y+c_1=0$ and $a_{2}x+b_{2}y+c_2=0$, we get

$\Rightarrow \frac{9}{3}=\frac{15}{k}\ne \frac{-2}{5}$

$\Rightarrow k=5$