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21.当n为自然数时,有x^6n+1/x^6n=2.21.当n为自然数时,有x^6n+1/x^6n=2证明:(1)x+1/x=-1==>x^6n+1/x^6n=2(2)x+1/x=1==>x^6n+1/x^6n=2

题目详情
21.当n为自然数时,有x^6n+1/x^6n=2 .
21.当n为自然数时,有x^6n+1/x^6n=2
证明:(1)x+1/x=-1 ==>x^6n+1/x^6n=2
(2)x+1/x=1 ==>x^6n+1/x^6n=2
▼优质解答
答案和解析
证明:(1) x+1/x=-1 ==> x^2+x+1=0 ==>x^3-1=(x-1)(x^2+x+1)=0==>x^3=1==>x^6=1
==>x^6n=1==>x^6n+1/x^6n=2
(2)x+1/x=1 ==> x^2-x+1=0 ==>x^3+1=(x+1)(x^2-x+1)=0==>x^3=-1==>x^6=1
==>x^6n=1==>x^6n+1/x^6n=2