作业帮如下图两题初三数学题,
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如下图两题初三数学题,
如下图两题初三数学题,
如下图两题初三数学题,
3）原式=(4-x)/(x-2)÷[（x²-4-12）/(x-2)]
=(4-x)/(x-2)÷[（x²-16）/(x-2)]
=(4-x)/(x-2)÷[(x+4)(x-4)/(x-2)]
=-1/(x+4)
=-1/(√3-4+4)
=-√3/3
4) 原式=(x-3)/2(x-2)÷[5-(x²-4)]/(x-2)
=(x-3)/2(x-2)÷(9-x²)/(x-2)
=(x-3)/2(x-2)÷(3+x)(3-x)/(x-2)
=-1/2(x+3)
=-1/2(√3-2+3)
=-1/2(√3+1)
=-(√3-1)/4
=(1-√3)/4
①原式=-(x-4)/(x-2)÷(x²-16)/(x-2)=-(x-4)/(x²-16)=-1/(x+4)
将x=√3-4代入，得 原式=-√3/3
②原式=(x-3)/[2(x-2)]÷(9-x²)/(x-2)=-(x-3)/[2(x²-9)]=-1/[2(x+3)]
将x=√3-2代入，得 原式=(1-√3)/4