Question

(-2x-1)^2=0 How to solve brackets, please help

Answer 1

not quite sure what you mean by brackets, but you can get the solution to this equation in a few steps:

(-2x - 1)² = 0  ... square root both sides to eliminate the squared binomial
√(-2x - 1)² = √0  ... simplify; the square is canceled out and the root of 0 brings you back to 0
-2x - 1 = 0  ... solve like a two-step equation
-2x = 1
x = -1/2 is your x-value.

Answer 2

All you have to know is 
( a + b )² = ( a + b ) ( a + b ) 
In this case, 
Since "a" is negative, make it into positive for easier simplification.

(-2x-1)² = 0
-(2x+1)² = 0
-[(2x+1) (2x+1)] = 0
Negative got eliminated when divided to 0
Thus,
x = -1/2  ,   x = -1/2