数学计算题,奇了怪了,算几次结果都不一样先化简再求值:x+3/3-x+x²-9/x²+6x+9,其中x=-2
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数学计算题,奇了怪了,算几次结果都不一样先化简再求值:x+3/3-x+x²-9/x²+6x+9,其中x=-2
数学计算题,奇了怪了,算几次结果都不一样
先化简再求值:x+3/3-x+x²-9/x²+6x+9,其中x=-2
数学计算题,奇了怪了,算几次结果都不一样先化简再求值:x+3/3-x+x²-9/x²+6x+9,其中x=-2
(x+3)/(3-x)+(x²-9)/(x²+6x+9)?
=(x+3)/(3-x)+(x+3)(x-3)/(x+3)²
=(x+3)/(3-x)+(x-3)/(x+3)
=-(x+3)(x+3)/[(x-3)(x+3)]+(x-3)(x-3)/[(x+3)(x-3)]
=[-(x+3)²+(x-3)²]/[(x-3)(x+3)]
=[(x-3)²-(x+3)²]/[(x-3)(x+3)]
=(x-3+x+3)(x-3-x-3)/[(x-3)(x+3)]
=(2x)(-6)/[(x-3)(x+3)]
=-12x/[(x-3)(x+3)]
x=-2
-12x/[(x-3)(x+3)]
=-12*(-2)/[(-2-3)(-2+3)]
=24/(-5)
=-24/5
x+1-x+x²-9/x²+6x+9=(x-x+6x)+x²-9/x²+(1+9)=6x+x²-9/x²+10
x=-2 6*(-2)+(-2)^2-9/4+10=-1/4
先简化
x+3/-(x-3)+(x+3)(x-3)/(x+3)²
=x+3/-(x-3)+(x-3)/(x+3)
=(x+3)²+(x-3)²/-(x-3)(x+3)
=2x²+18/-(x²-9)
=2×(-2)²+18/-[(-2)²-9]
=-26/5
结果是负五分之一二十六
负九分之八十
1. 先化简:
2. 将x=-2代入, 则结果为: 2*(4+9)/(4-9)=-26/5=-5.2
如果你的虱子是这个的话:(x+3)/(3-x)+(x²-9)/(x²+6x+9)
=(x+3)/(3-x)+(x+3)(x-3)/【(3+x)*(3+x)】
=(x+3)/(3-x)+(x-3)/(x+3)
=(2*x*x+2*9)/(x*x-9)【通分就可以得到这个式子】
=【2*(-2)*(-2)+18】/【(-2)*(-2)-9】
...
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如果你的虱子是这个的话:(x+3)/(3-x)+(x²-9)/(x²+6x+9)
=(x+3)/(3-x)+(x+3)(x-3)/【(3+x)*(3+x)】
=(x+3)/(3-x)+(x-3)/(x+3)
=(2*x*x+2*9)/(x*x-9)【通分就可以得到这个式子】
=【2*(-2)*(-2)+18】/【(-2)*(-2)-9】
=26/(-5)
=-26/5=-5.2
收起
(x+3)/(3-x)+(x+3)(x-3)/(x+3)²
=(x+3)/(3-x)+(x-3)/(x+3)
= -4.8