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(1)若X满足X+1/X=3,求X^2/X^4+X^2+1的值(2)....
(1)若X满足X+1/X=3,求X^2/X^4+X^2+1的值(2)若X满足X^2+X-1=0,求X^14+1/X^14的值...
(1)若X满足X+1/X=3,求X^2/X^4+X^2+1的值
(2)若X满足X^2+X-1=0,求X^14+1/X^14的值 展开
(2)若X满足X^2+X-1=0,求X^14+1/X^14的值 展开
1个回答
2013-04-24
展开全部
(1)∵X+1/X=3
∴(X+1/X)^2=X^2+1/X^2+2=9
∴X^2+1/X^2=7
∴X^2/(X^4+X^2+1)=1/(X^2+1+1/X^2)=1/8
(2)∵X^2+X-1=0
∴X+1-1/X=0即X-1/X=-1
∴X^2-2+1/X^2=1,即X^2+1/X^2=3
接下来方法类似
∴(X+1/X)^2=X^2+1/X^2+2=9
∴X^2+1/X^2=7
∴X^2/(X^4+X^2+1)=1/(X^2+1+1/X^2)=1/8
(2)∵X^2+X-1=0
∴X+1-1/X=0即X-1/X=-1
∴X^2-2+1/X^2=1,即X^2+1/X^2=3
接下来方法类似
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