4x2 - 9y2 + 4x - 6y
= (2x - 3y)(2x + 3y) + 2(2x - 3y)
= (2x - 3y)(2x + 3y + 2)
\(4x^2-9y^2+4x-6y\)
\(=\left(4x^2+4x+1\right)-\left(9y^2+6y+1\right)\)
\(=\left(2x+1\right)^2-\left(3y+1\right)^2\)
\(=\left(2x+1-3y-1\right)\left(2x+1+3y+1\right)\)
\(=\left(2x-3y\right)\left(2x+3y+2\right)\)