化简(x^2-4\x^2-4x+4+2-x\x+2)。其中x=-3
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解决时间 2021-01-24 10:38
- 提问者网友：临风不自傲
- 2021-01-23 17:31
化简(x^2-4\x^2-4x+4+2-x\x+2)。其中x=-3
最佳答案
- 五星知识达人网友：掌灯师
- 2021-01-23 18:35
原式=(x+2)(x-2)/(x-2)^2-(x-2)/(x+2)
=(x+2)/(x-2)-(x-2)/(x+2)
=[(x+2)^2-(x-2)^2]/(x+2)(x-2)
=(x+2+x-2)(x+2-x+2)/(x+2)(x-2)
=4x/(x+2)(x-2)
=-12/[(-1)×(-5)]
=-12/5
=(x+2)/(x-2)-(x-2)/(x+2)
=[(x+2)^2-(x-2)^2]/(x+2)(x-2)
=(x+2+x-2)(x+2-x+2)/(x+2)(x-2)
=4x/(x+2)(x-2)
=-12/[(-1)×(-5)]
=-12/5
全部回答
- 1楼网友：北城痞子
- 2021-01-23 19:42
(x²-4)/(x²-4x+4)+(2-x)/(x+2)
(x²-2²)/(x²-2×2x+2²)+(2-x)/(x+2)
=(x+2)(x-2)/(x-2)²-(x-2)/(x+2)
=(x+2)/(x-2)- (x-2)/(x+2)
=[(x+2)(x+2)-(x-2)(x-2)]/[(x-2)(x+2)]
=[(x+2)²-(x-2)²]/[(x-2)(x+2)]
=[(x+2+x-2)(x+2-x+2)]/(x²-4)
=4(2x)/(x²-4)
=8x/(x²-4)
=8×(-3)/((-3)²-4)
=-24/(9-4)
=-24/5
(x²-2²)/(x²-2×2x+2²)+(2-x)/(x+2)
=(x+2)(x-2)/(x-2)²-(x-2)/(x+2)
=(x+2)/(x-2)- (x-2)/(x+2)
=[(x+2)(x+2)-(x-2)(x-2)]/[(x-2)(x+2)]
=[(x+2)²-(x-2)²]/[(x-2)(x+2)]
=[(x+2+x-2)(x+2-x+2)]/(x²-4)
=4(2x)/(x²-4)
=8x/(x²-4)
=8×(-3)/((-3)²-4)
=-24/(9-4)
=-24/5
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