Question 68424
{{{x^2 = -81}}}
1. To solve for x, extract the square root both sides
{{{sqrt (x^2) = sqrt (-81)}}} 
<br>
{{{ x = sqrt (-81)}}}
{{{ x = sqrt ((-1)(81))}}}

<br><i>Note: {{{sqrt (-1) = i }}}</i> and {{{sqrt(81) = 9}}}
{{{highlight (x = 9i)}}}