Solve this
Question:

$3 x^{2}-243=0$

Solution:

Given:

$3 x^{2}-243=0$

$\Rightarrow 3\left(x^{2}-81\right)=0$

$\Rightarrow(x)^{2}-(9)^{2}=0$

$\Rightarrow(x+9)(x-9)=0$

$\Rightarrow x+9=0$ or $x-9=0$

$\Rightarrow x=-9$ or $x=9$

Hence, $-9$ and 9 are the roots of the equation $3 x^{2}-243=0 .$