一.已知a+(1/a)=2,求a^2+(1/a^2)的值二.已知a-(1/a)=3/2,求a^2+(1/a^2)的值

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一.已知a+(1/a)=2,求a^2+(1/a^2)的值二.已知a-(1/a)=3/2,求a^2+(1/a^2)的值一.已知a+(1/a)=2,求a^2+(1/a^2)的值二.已知a-(1/a)=3/

一.已知a+(1/a)=2,求a^2+(1/a^2)的值二.已知a-(1/a)=3/2,求a^2+(1/a^2)的值
一.已知a+(1/a)=2,求a^2+(1/a^2)的值
二.已知a-(1/a)=3/2,求a^2+(1/a^2)的值

一.已知a+(1/a)=2,求a^2+(1/a^2)的值二.已知a-(1/a)=3/2,求a^2+(1/a^2)的值
4=[a+(1/a)]^2=a^2+(1/a^2)+2
a^2+(1/a^2)=2
9/4=[a-(1/a)]^2=a^2+(1/a^2)-2
a^2+(1/a^2)=17/4

a^2+(1/a^2)
=[a+(1/a)]^2-2
=4-2
=2
解析
[a+(1/a)]^2
=a^2+(1/a^2)+2a^2*(1/a^2)
=a^2+(1/a^2)+2
a^2+(1/a^2)
=[a-(1/a)]^2+2
=9/4+2
=17/4
=4.25
解析
[a-(1/a)]^2
=a^2+(1/a^2)-2a^2*(1/a^2)
=a^2+(1/a^2)-2

a^2-2a+1=0
解得:a=1
则:a^2+(1/a^2)=2
2a^2+3a-2=0
解得:a=1/2或a=-2
则: a^2+(1/a^2)=4.25