Question

What are the roots of the quadratic equation x²-81=0

Answer 1

x = ± 9

Explanation:

Given

x² - 81 = 0 ( add 81 to both sides )

x² = 81 ( take the square root of both sides )

x = ±
`√(81)` = ± 9

Thus roots are x = - 9, x = 9

Answer 2

What are the roots of the quadratic equation x²-81=0