问题 选择题

将2(x+y)-3(x-y)-4(x+y)+5(x-y)-3(x-y)合并同类项得(  )

A.-3x-y

B.-2(x+y)

C.-x+y

D.-2(x+y)-(x-y)

答案

原式=2(x+y)-4(x+y)-3(x-y)+5(x-y)-3(x-y)

=-2(x+y)-(x-y)

=-2x-2y-x+y

=-3x-y,

故选A.

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