x/(x^2-x+1)=1/7,求:x^2/(x^4+x^2+1)的值
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x/(x^2-x+1)=1/7
(x²-x+1)/x=7
x-1+1/x=7
x+1/x=8
(x^4+x^2+1)/x²
=x²+1+1/x²
=﹙x+1/x)²-1
=8²-1
=63
∴x^2/(x^4+x^2+1)=1/63
(x²-x+1)/x=7
x-1+1/x=7
x+1/x=8
(x^4+x^2+1)/x²
=x²+1+1/x²
=﹙x+1/x)²-1
=8²-1
=63
∴x^2/(x^4+x^2+1)=1/63
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展开全部
x/x^2-x+1=1/7
1/(x-1+1/x)=1/7
1/x+x-1=7
x+1/x=8
∴x^2/x^4+x^2+1
=1/x^2+(1/x^2)+1
=1/(x+1/x)^2-1
=1/(64-1)
=1/63
1/(x-1+1/x)=1/7
1/x+x-1=7
x+1/x=8
∴x^2/x^4+x^2+1
=1/x^2+(1/x^2)+1
=1/(x+1/x)^2-1
=1/(64-1)
=1/63
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