SOLUTION: Solve by completing the square. x2 + 2x – 15 = 0

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Question 49409: Solve by completing the square.
x2 + 2x – 15 = 0
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solve by completing the square:
x%5E2%2B2x-15+=+0 First, add 15 to both sides of the equation.
x%5E2%2B2x+=+15
Since the coefficient of the x%5E2 term is 1, you can complete the square by adding the square of half the coefficient of the x-term, which is: %282%2F2%29%5E2+=+1, to both sides of the equation.
x%5E2%2B2x%2B1+=+16 Now factor the left sides of the equation.
%28x%2B1%29%5E2+=+16 Next, take the square root of both sides.
x%2B1+=+sqrt%2816%29 and x%2B1+=+-sqrt%2816%29 Finally, solve for x.
x+=+-1%2Bsqrt%2816%29 x+=+-1%2B4 x+=+3
x+=+-1-sqrt%2816%29 x+=+-1-4 x+=+-5