Verified Answer :

x² - 81 = 0
x² = 81
x = √81
x = 9

Answer:

x=9 x=-9

Step-by-step explanation:

\(x^{2}\)-81=0

  +81 +81

\(x^{2}\)=81

\(\sqrt{x^{2} }\)=\(\sqrt{81}\)

x=±9

the person above me was right just didn't finish putting it all in.