已知A=5x3-7x+2x2,B=-2x2-4+6x3
(1)求A+B;
(2)求A-B.
分析:(1)根據(jù)A=5x3-7x+2x2,B=-2x2-4+6x3,列出A+B的式子,再合并同類項(xiàng)即可;
(2)根據(jù)A=5x3-7x+2x2,B=-2x2-4+6x3,列出A-B的式子,再合并同類項(xiàng)即可.
解答:解:(1)∵A=5x3-7x+2x2,B=-2x2-4+6x3,
∴A+B=(5x3-7x+2x2)+(-2x2-4+6x3
=5x3-7x+2x2-2x2-4+6x3
=11x3-7x-4;

(2)∵A=5x3-7x+2x2,B=-2x2-4+6x3,
∴A-B=(5x3-7x+2x2)-(-2x2-4+6x3
=5x3-7x+2x2+2x2+4-6x3
=-x3+4x2-7x+4.
點(diǎn)評:本題考查的是整式的加減,熟知整式的加減實(shí)質(zhì)上就是合并同類項(xiàng)是解答此題的關(guān)鍵.
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已知A=5x3-7x+2x2,B=-2x2-4+6x3
(1)求A+B;
(2)求A-B.

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