X满足X^2+5x-1=0 ,求X^2+1/X^2=?
答案:4 悬赏:80
解决时间 2021-03-29 14:16
- 提问者网友:记得曾经
- 2021-03-28 16:30
X满足X^2+5x-1=0 ,求X^2+1/X^2=?
最佳答案
- 二级知识专家网友:野心和家
- 2021-03-08 14:10
x^2+5x-1=0
x^2-1=-5x
两边同除以x
x-1/x=-5
x^2+1/x^2
=(x-1/x)^2+2
=(-5)^2+2
=25+2
=27
x^2-1=-5x
两边同除以x
x-1/x=-5
x^2+1/x^2
=(x-1/x)^2+2
=(-5)^2+2
=25+2
=27
全部回答
- 1楼网友:厌今念往
- 2019-09-23 05:11
x^2+5x-1=0
x^2-1=-5x
两边同除以x
x-1/x=-5.x^2+1/x^2 =(x-1/x)^2+2 =(-5)^2+2 =25+2 =27
- 2楼网友:何必打扰
- 2020-05-12 08:36
x^2+1/x^2=(x+1/x)^2-2=5x5-2=23 (x^2-5x+1=0 则x+1/x=5
- 3楼网友:邪性洒脱
- 2019-06-18 23:39
^2+5x-1=0
x+5-1/x=-5
X^2+1/X^2=(x-1/x=0
x-1/
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