Question

Solve. x² – 81 = 0 (1 point)

0
–9
–9, 9
9

Answer 1

Hint:\[x ^{2} = a \rightarrow x = \pm \sqrt{a} \]if a is positive.

Answer 2

is it 9

Answer 3

Note the plus-minus sign preceding the root.

For example:
\[2^{2} = 2\times2 = 4\]\[(-2)^{2} = (-2)\times(-2) = 4\]
This means that quadratic equations will have more then one answer.