Question

If the distance between the two points $(-1, a )$ and $(-1, -4a )$ is $10$ units, then the values of $a$ are

• A. $\pm 1$
• B. $\pm 2$
• C. $\pm 3$
• D. $\pm 4$

Answer 1

Answer: (B)

$\pm 2$

Answer 2

Given, distance between points $(-1, a)$ and $(-1,-4 a)$ is 10
$\therefore \sqrt{0^{2}+(-5 a)^{2}}=10$
$\Rightarrow 25 a^{2}=100$
$\Rightarrow a^{2}=4$
$\Rightarrow a=\pm 2$