问题 填空题

合并同类项:x2y-xy2+3x2y-xy2=______.

答案

x2y-xy2+3x2y-xy2

=x2y+3x2y-xy2-xy2

=(1+3)x2y-(1+1)xy2

=4x2y-2xy2

故答案为:4x2y-2xy2

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