SOLUTION: solve using square root property (x-3)^2=81

Algebra ->  Square-cubic-other-roots -> SOLUTION: solve using square root property (x-3)^2=81      Log On


   

Question 884344: solve using square root property (x-3)^2=81
Answer by DrBeeee(684) About Me  (Show Source):
You can put this solution on YOUR website!
Given:
(1) (x-3)^2 = 81
Take the square root of both sides of (1), equating the positive root (principal root) of the left side to the +/- root of the right side to get
(2) x - 3 = +/- sqrt(81) or
(3) x - 3 = +/- 9 or
(4) x = 3 +/- 9 or
(5) x = {12,-6}
Check the answers using (1).
Is ((12-3)^2 = 81)?
Is ((9)^2 = 81)?
Is (81 = 81)? Yes
Is ((-6-3)^2 = 81)?
Is ((-9)^2 = 81)?
Is (81 = 81)? Yes
Answer: x = {-6,12}