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