a: \(=\left(x+1\right)^3-27z^3\)
\(=\left(x+1-3z\right)\left[\left(x+1\right)^2+3z\left(x+1\right)+9z^2\right]\)
\(=\left(x-3z+1\right)\left(x^2+2x+1+3xz+3z+9z^2\right)\)
b: \(4x^2+4x+1-9y^2\)
\(=\left(2x+1\right)^2-9y^2\)
\(=\left(2x+1+3y\right)\left(2x+1-3y\right)\)
c: \(=x^2-\left(y^2-2yz+z^2\right)\)
\(=x^2-\left(y-z\right)^2\)
\(=\left(x-y+z\right)\left(x+y-z\right)\)