1.-10x^2y-5xy^2+15xy=5xy(3-2x-y；
2.（2a+b)(2a-3b)+a(2a+b)=(2a+b)[(2a-3b)+a]=(2a-3b)(3a-3b)=3(2a-3b)(a-b)；
3.5a^3b（a-b）^3-10a^4b^3（b-a）^2=5a³b(a-b)²[(a-b)-2ab²]=5a³b(a-b)²(a-b2ab²)；
4.(3a-4b)(7a-8b)+(11a-12b)(8b-7a)=(3a-4b)(7a-8b)-(11a-12b)(7a-8b)=(7a-8b)[(3a-4b)-(11a-12b)]=(7a-8b)(8a-8b)=8(7a-8b)(a-b)；
5.x(b+c-d)-y(d-b-c)-c-b+d=x(b+c-d)+y(b+c-d)-(b+c-d)=(b+c-d)(x+y-1),6.（x+3)^2-(x+3)=(x+3)[(x+3)-1]=(x+3)(x+2)