问题
解答题
合并同类项.
(1)5(2x-7y)-3(4x-10y);
(2)(5a-3b)-3(a2-2b);
(3)3(3a2-2ab)-2(4a2-ab);
(4)2x-[2(x+3y)-3(x-2y)].
答案
(1)5(2x-7y)-3(4x-10y)=10x-35y-12x+30y=-2x-5y;
(2)(5a-3b)-3(a2-2b)=5a-3b-3a2+6b=5a-3a2+3b;
(3)3(3a2-2ab)-2(4a2-ab)=9a2-6ab-8a2+2ab=a2-4ab;
(4)2x-[2(x+3y)-3(x-2y)]=2x-(-x+12y)=3x-12y.