2a^{4} b^{3} -2a^{3} b^{4} +6a^{2} b^{2} =2a^{2} b^{2}( a^{2}b-ab^{2} +3)
x^{2} -3x-3y- y^{2} =( x^{2} - y^{2} )-3(x+y)=(x-y)(x+y)-3(x+y)=(x-y)(x+y)-3(x+y)=(x+y)(x-y-3)
2a^{4} b^{3} -2a^{3} b^{4} +6a^{2} b^{2} =2a^{2} b^{2}( a^{2}b-ab^{2} +3)
x^{2} -3x-3y- y^{2} =( x^{2} - y^{2} )-3(x+y)=(x-y)(x+y)-3(x+y)=(x-y)(x+y)-3(x+y)=(x+y)(x-y-3)