(3x^2+9x+7)/(x+1)-(2x^2+4x-3)/(x-1)-(x^3+x+1)/(x^2-1)这个题.

笨小虾2022-10-04 11:39:541条回答

(3x^2+9x+7)/(x+1)-(2x^2+4x-3)/(x-1)-(x^3+x+1)/(x^2-1)这个题.
难道到了[(3x^2+9x+7)(x-1)-(2x^2+4x-3)(x+1)-(x^3+x+1)]/(x^2-1)这一步就直接出了答案-(4x+5)/(x^2-1)了吗?

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bodazhang 共回答了17个问题 | 采纳率82.4%
(3x²+9x+7)/(x+1)-(2x²+4x-3)/(x-1)-(x^3+x+1)/(x²-1)
=(3x²+9x+7)/(x+1)-(2x²+4x-3)/(x-1)-(x^3+x+1)/[(x+1)(x-1)]
=[(3x²+9x+7)(x-1)-(2x²+4x-3)(x+1)-(x^3+x+1)]/[(x+1)(x-1)]
=[3x^3+9x²+7x-3x²-9x-7-2x^3-4x²+3x-2x²-4x+3-x^3-x-1]/[(x+1)(x-1)]
=(5x-5)/[(x+1)(x-1)]
=5/(x+1)
1年前

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SORRY打错了
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不许通分,有更好的办法
只是第一步不许通分啊
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计算:再问一题:(3x^2+9x+7)/(x+1)-(2x^2-4x+3)/(x-1)-(x^3+x+1)/(x^2-1
计算:
再问一题:
(3x^2+9x+7)/(x+1)-(2x^2-4x+3)/(x-1)-(x^3+x+1)/(x^2-1)=?
虽然看着有点烦
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解方程(3x^2+9x+7)/(x+1)-(2x^2+4x-3)/(x-1)-(x^3+x+1)/(x^2-1)=0
解方程(3x^2+9x+7)/(x+1)-(2x^2+4x-3)/(x-1)-(x^3+x+1)/(x^2-1)=0
别从网上随便搜一个,要求自己答.
如果打字麻烦,可以发图或者用简便的办法,
eligang1年前1
7799650 共回答了26个问题 | 采纳率92.3%
方程两边同时乘以x²-1:
(3x²+9x+7)(x-1)-(2x²+4x-3)(x+1)-(x³+x+1)=0
3x^3+9x^2+7x-3x^2-9x-7-(2x^3+4x^2-3X+2x^2+4x-3)-x^3-x-1=0
3x^3+6x^2-2x-7-2x^3-4x^2+3x-2x^2-4x+3-x^3-x-1=0
0*x^3+0*x^2-4x-7-1+3=0
-4x-5=0
-4x=5x
x=-5/4
经检验x=-5/4为原方程的解.
望采纳!谢谢!
求(3x^2+9x+7)/(x+1)-(2x^2+5x-3)/(x-1)-(x^3+x-1)/(x^2-1)的值
zmj52591年前1
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(3x^2+9x+7)/(x+1)-(2x^2+5x-3)/(x-1)-(x^3+x-1)/(x^2-1)
=[(3x²+9x+7)(x-1)-(2x²+5x-3)(x+1)-(x³+x-1)]/(x²-1)
=[3x³-3x²+9x²-9x+7x-7-(2x³+2x²+5x²+5x-3x-3)-(x³+x-1)]/(x²-1)
=(3x³+6x²-2x-7-2x³-7x²-2x+3-x³-x+1)/(x²-1)
=(-x²-5x-3)/(x²-1)
=-(x²+5x+3)/(x²-1)
如果本题有什么不明白可以追问,