Question

If the lines x + q = 0, y − 2 = 0 and 3x + 2y + 5 = 0 are concurrent, then the value of q will be
(a) 1
(b) 2
(c) 3
(d) 5

Answer 1

(c) 3

The lines x + q = 0, y − 2 = 0 and 3x + 2y + 5 = 0 are concurrent.

$$\begin{gathered} \therefore \left|\begin{array}{ccc}1& 0& q\\ 0& 1& -2\\ 3& 2& 5\end{array}\right|=0 \\ \Rightarrow 1\left(5+4\right)-0+q\left(0-3\right)=0 \\ \Rightarrow 3q=9 \\ \Rightarrow q=3 \end{gathered}$$