问题 解答题

化简:

(1)-a+2(a+b)-4(a+b)    

(2)x2y-(6xy+3x2y-xy2)+(5xy+2x2y)

答案

(1)原式=-a+2a+2b-4a-4b

=-2b-3a;

(2)原式=x2y-6xy-3x2y+xy2+5xy+2x2y

=(1-3+2)x2y-(6-5)xy+xy2

=xy+xy2

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