Question

Solve for $a:a^2-36=0$

• A. $a=6$
• B. $a=-6$
• C. $a=-6,6$
• D. $a=4,9$

Answer 1

Answer: (C)

$a=-6,6$

Given, $a^2-36=0$
$\Rightarrow a^2-6a+6a-36=0$
$\Rightarrow a(a-6)+6(a-6)=0$
$\Rightarrow (a-6)(a+6)$
$\Rightarrow a-6=0$ or $a+6=0$
$\Rightarrow a=-6$ or $6$
Hence, required solution for $a$ is $\{-6,6\}$.