## anonymous one year ago Solve x^2 + 10x - 11 = 0 by completing the square Ok, so I need help with this, I have the answer and I know how to do it, I just want to check it.

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1. campbell_st

ok... to you need to group a few things $x^2 + 10x = 11$ to complete the square find half of 10 and then square it... that's the value that makes the perfect square then add it to both sides..

2. anonymous

Ok that's a bit different then how I learned it but I think it's pretty much the same thing.. I would do x^2 + 10x + 25=11+25 Then group it to where it's (X+5)^2=36 Then you would put the (x+5)^2 under a radical sign, and the 36 under the radical sign, and you can't forget the plus and minus sign

3. campbell_st

that's correct

4. anonymous

But I don't know what to do after

5. campbell_st

ok... so when you take the square root there are 2 solutions, the positive and negative so take the square root of both sides $x + 5 = \pm \sqrt{36} ~~or~~~x + 5 = \pm 6$ now subtract 5 from both sides of the equation and you get $x = -5 \pm 6$ so you ahve 2 equations x = -5 -6 and x = -5 + 6 does that make sense

6. anonymous

Yes, see, I did all that But I had three instead of six. But thank you so much! I'm glad I checked with someone :)