Question

Find x in $x^2-9=72$.

• A. 7
• B. 9
• C. 8
• D. 10

Answer 1

The correct option is B

9

$x^2-9=72$
$x^2=81$
We know that $81=9^2$
$x^2=9^2$
So, $x=9$
Remember that $(-9{)}^2=81$ too.
But among the options, the correct answer is 9.