SOLUTION: solve the quadratic equation: {{{(x+3)^2=81}}} thanks a lot

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Question 51610: solve the quadratic equation:
%28x%2B3%29%5E2=81
thanks a lot
Answer by rchill(405) About Me  (Show Source):
You can put this solution on YOUR website!
Doing it the easy way: Let's take the square root of both sides: sqrt%28%28x%2B3%29%5E2%29=sqrt%2881%29, which simplifies to x%2B3=9. Because we are squaring the (x+3) though, that means that we could have two solutions, one positive and one negative (x%2B3=-9. Solving for the first equation, subtract 3 from both sides: x%2B3-3=9-3, which simplifies to x=6. Now solve for the second equation: x%2B3-3=-9-3, which simplifies to x=-12. So there are two solutions for x: 6 and -12. An alternative way of solving is by using the quadratic equation and discriminant.