【1】x^2y-5xy^2+4x^2y-2xy^2 - 知识问答

【1】x^2y-5xy^2+4x^2y-2xy^2 【2】-3mn+2mn-5mn 【3】-3a^2+2a-1+a^2-

1个回答

【1】x^2y-5xy^2+4x^2y-2xy^2
=(x^2y+4x^2y)+(-5xy^2-2xy^2)
=5x^2y-7xy^2
【2】-3mn+2mn-5mn
=(-3+2-5)mn
=-8mn
【3】-3a^2+2a-1+a^2-5a-8
=(-3a^2+a^2)+(2a-5a)+(-1-8)
=-2a^2-3a-9

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