Question

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.

Answer 1

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..

Answer 2

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

Answer 3

that's correct

Answer 4

But I don't know what to do after

Answer 5

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

Answer 6

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 :)