how do you solve this can you do this with the steps do I an understand them,please.

(x-9)^2=81

The way it sits, both sides are a perfect square, so yo simply take the square root of both sides.

(x-9) = ± 9
x = 9 ± 9
x = 0 or x = 18

or

you could expand it ....

x^2 - 18x + 81 = 81
x^2 - 18x = 0
x(x - 18) = 0
x = 0 or x = 18