Question

b. $2x^2 + 72 = 0$

Explanation:

Step1: Isolate the $x^2$ term

Subtract 72 from both sides:
$2x^2 = -72$

Step2: Solve for $x^2$

Divide both sides by 2:
$x^2 = \frac{-72}{2} = -36$

Step3: Solve for $x$

Take square root of both sides, using $i=\sqrt{-1}$:
$x = \pm\sqrt{-36} = \pm 6i$

Answer:

$x = 6i$ and $x = -6i$