Meaning there's only 1 real root, complete the square and you get the answer.
We're going to use this formula, so if x² = 4x² then x = 2x
and if y² = 1 then y = 1
Straight to formula
Because (2x+1)² is basically (2x+1)(2x+1), we get the same value of x.
So the answer is x = -1/2
(When D>0, there are 2 real roots.)
(When D=0, there are only 1 real root.)
(When D<0, there are no real roots, but 2 complex roots.)