a-(1/a)=5,则a^2+(1/a^2)=?已知a-(1/a)=5,则a^2+(1/a^2)=?
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![a-(1/a)=5,则a^2+(1/a^2)=?已知a-(1/a)=5,则a^2+(1/a^2)=?](/uploads/image/z/12394340-44-0.jpg?t=a-%EF%BC%881%2Fa%EF%BC%89%3D5%2C%E5%88%99a%5E2%2B%281%2Fa%5E2%29%3D%3F%E5%B7%B2%E7%9F%A5a-%EF%BC%881%2Fa%EF%BC%89%3D5%2C%E5%88%99a%5E2%2B%281%2Fa%5E2%29%3D%3F)
a-(1/a)=5,则a^2+(1/a^2)=?已知a-(1/a)=5,则a^2+(1/a^2)=?
a-(1/a)=5,则a^2+(1/a^2)=?
已知a-(1/a)=5,则a^2+(1/a^2)=?
a-(1/a)=5,则a^2+(1/a^2)=?已知a-(1/a)=5,则a^2+(1/a^2)=?
a²+1/a²
=(a-1/a)²-2
=25-2
=23
(a-(1/a))^2=a^2+(1/a^2)-2=25
a^2+(1/a^2)=27
由题意知
因为a-1/a=5
所以(a-1/a)^2=25
又a^2-(1/a)^2=(a-1/a)^2-2
所以原式=25-2=23
思路(a-b)^2+2ab=a^2+b^2