原式=4x^2-12xy+9y^2-(3xy-xy+9x^2-3xy)
=4x^2-12xy+9x^2-3xy+xy-9x^2+3xy
=4x^2-12xy+xy
=4x^2-11xy
=x(4x-11y)
因式分解（2X-3Y)^2-（y+3X)(3X-Y)是因式分解,不是计算,急
原式=4x^2-12xy+9y^2-(3xy-xy+9x^2-3xy)
=4x^2-12xy+9x^2-3xy+xy-9x^2+3xy
=4x^2-12xy+xy
=4x^2-11xy
=x(4x-11y)