合并同类项1.5ab-4a^2b^2-ab^2-4a^2b^2-7ab^2+3ab =(1.5+3)ab-(4+4)a^2b^2-(1+7)ab^2=4.5ab-8a^2b^2-8ab^2-x^3y-1/2x^3y-xy^3-1/2x^3y+2x^3y-5/3xy^3=-(1+1/2+1/2+2)x^3y-(1+5/3)xy^3=-4x^3y-8/3xy^3不是的那个不是1.5 （1.只是题号）但是辛苦你了~~5ab-4a^2b^2-ab^2-4a^2b^2-7ab^2+3ab =(5+3)ab-(4+4)a^2b^2-(1+7)ab^2=8ab-8a^2b^2-8ab^2