Question 666507: Direction are complete the square.
x^2+2x=5
Am I suppose to set this to zero? When I do, I don't know what would make the sum of 2 and give me -5.
I get to x^2+2x-5=0
Answer by Leaf W.(135)   (Show Source):
You can put this solution on YOUR website! 
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No, you are not supposed to set this equal to zero when you complete the square; that is for quadratic formula. It is in perfect starting format the way it is -- the coefficient of  (number it is multiplied; for example, the coefficient of x in 2x is 2) is 1, which is exactly what you want. Also, the two x terms (x^2 and 2x) are on the left of the equation, and the 5 is on the right, which is also correct.
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Divide the coefficient of the "x" term (in this case, the x term would be 2x, so its coefficient would be the number before the x, 2) in half. This would give you  , or 1.
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Square this number:  = 1
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Add the result to both sides of the equation: 
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Simplify the right side of the equation: 
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Factor the left side of the equation: 
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Square root both sides. Remember that the right side could be either the positive or the negative square root: x + 1 = ±
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Isolate the x by subtracting 1 from both sides: x = -1 ±
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Your final answer is x = -1 ± .
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