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若x^2+y^2=5,xy=2,则1/x+1/y=?
人气:157 ℃ 时间:2020-06-23 18:53:06
解答
x^2+y^2=5,xy=2
则(x+y)²=x²+y²+2xy=5+4=9
则x+y=3或-3
1/x+1/y
=y/(xy)+x/(xy)
=(x+y)/(xy)
=3/2或-3/2
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