Question

how can you complete the square for a quadratic expression

Answer 1

Okay, say that you have something like, x^2+4x = 9
complete the square method is just (b/2)^2, where b is the 4 in this case. Then we have
x^2+4x+4 = 9
We factor and get
(x+2)^2 = 9
And continue solving from there

Answer 2

ok but i need the explanation on how to do it

Answer 3

just gave u one.
basically just take (b/2)^2 and add that on both sides, you can then factor that out evenly (what I mean is that you will have the same terms in both factors, like (x+4) and (x+4) or in the above example we had x+2 and x+2. Afterwards, well x+4) (x+4) = (x+4)^2 so we square root both sides and then solve for x.

Answer 4

ok