Question

If $P\left(\frac{a}{2},4\right)$ is the midpoint of the line segment joining the points A(−6, 5) and B(−2, 3) then the value of a is [CBSE 2011]
(a) −8 (b) 3 (c) −4 (d) 4

Answer 1

The point $P\left(\frac{a}{2},4\right)$ is the midpoint of the line segment joining the points A(−6, 5) and B(−2, 3). So
$$\begin{gathered} \frac{a}{2}=\frac{-6-2}{2} \\ \Rightarrow \frac{a}{2}=-4 \\ \Rightarrow a=-8 \end{gathered}$$
Hence, the correct answer is option (a).