Question

Three lines 3x – y = 2, 5x + ay = 3 and 2x + y = 3 are concurrent, then a =

• A. 2
• B. 3
• C. –1
• D. –2

Answer 1

Answer: (D)

–2

Answer 2

Lines are concurrent

\ $\left| \begin{array} { c c c } 3 & - 1 & - 2 \\ 5 & \mathrm { a } & - 3 \\ 2 & 1 & - 3 \end{array} \right|$ = 0

Ž 3(–3a +3) + 1(–15 + 6) –2(5 –2a) = 0

Ž a = –2