数学-化简先化简,再求值;其中a=√3-3
2009-12-23 12:18:33不***
先化简,再求值;其中a=√3-3数学-化简先化简,再求值;其中a=√3-3:(a-3)/(2a-4)/[5/(a-2)-a-2]
=(a-3)/(2a-4)/[(5-a(a-2)-2(a-2?
最佳回答
(a-3)/(2a-4)/[5/(a-2)-a-2]
=(a-3)/(2a-4)/[(5-a(a-2)-2(a-2))/(a-2)]
=(a-3)/[2(a-2)]*(a-2)/(5-a^2+2a-2a+4)
=(a-3)/[2(9-a^2)]
=(a-3)/[2(3-a)(3+a)]
=-1/[2(3+a)]
a=√3-3
原式=-1/[2(3+a)]
=-1/[2(3+√3-3)]
=-√3/6
2009-12-23 12:36:38
原式=(a-3)/(2a-4)÷ [(9-a^2)/(a-2)]
=(a-3)/[2(a-2)]×{(a-2)/[(3+a)(3-a)]}
=-1/[2(3+a)]
把a=√3-3代入上式得:
=-1/[2(3+√3-3)]
=-1/(2√3)
=-√3/6
2009-12-23 12:39:48
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