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.

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