Question

If $(\frac{a}{3},4)$ is the midpoint of the line segment joining $A(-6,5)$ and $B(-2,3)$, find $a$.

• A. $-4$
• B. $-12$
• C. $12$
• D. $-6$

Answer 1

The correct option is B $-12$

Given the point A(-6,5) and B(-2,3) $(\frac{a}{3},4)$ is the middle of AB

$\Rightarrow (\frac{-2-6}{2},\frac{3+5}{2})=(\frac{a}{3},4)\Rightarrow \frac{-8}{2}=\frac{a}{3}\therefore a=-\frac{24}{2}=-12$