a: \(=-\left(2x-1\right)^2\)
b: \(=\left(2x+1\right)^2-\left(2x-2\right)^2\)
\(=\left(2x+1-2x+2\right)\left(2x+1+2x-2\right)\)
\(=3\left(4x-1\right)\)
c: \(=\left(2x+y\right)^2-\left(2x-3\right)^2\)
\(=\left(2x+y-2x+3\right)\left(2x+y+2x-3\right)\)
\(=\left(y+3\right)\left(4x+y-3\right)\)
d: \(=\left(x+1-2y^2\right)^2\)