设x-1\x=3,求x^10+x^8+x^2+1\x^10+x^6+x^4+1的值,
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![设x-1\x=3,求x^10+x^8+x^2+1\x^10+x^6+x^4+1的值,](/uploads/image/z/9256601-65-1.jpg?t=%E8%AE%BEx-1%5Cx%3D3%2C%E6%B1%82x%5E10%2Bx%5E8%2Bx%5E2%2B1%5Cx%5E10%2Bx%5E6%2Bx%5E4%2B1%E7%9A%84%E5%80%BC%2C)
设x-1\x=3,求x^10+x^8+x^2+1\x^10+x^6+x^4+1的值,
设x-1\x=3,求x^10+x^8+x^2+1\x^10+x^6+x^4+1的值,
设x-1\x=3,求x^10+x^8+x^2+1\x^10+x^6+x^4+1的值,
x-1/x=3
=>x^2+1/x^2=(x-1/x)^2+2=3^2+2=11
(x+1/x)^2=(x-1/x)^2+4=9+4=13
=>x+1/x=√13
=>x^3+1/x^3=(x+1/x)(x^2+1/x^2-1)=√13*(11-1)=10√3
=>x^4+1/x^4=(x^2+1/x^2)^2-2=11^2-2=119
(x^10+x^8+x^2+1)/x^10+x^6+x^4+1
=(x^6(x^4+1/x^4)+x^4(x^4+1/x^4))/(x^7(x^3+1/x^3)+x^3(x^3+1/x^3))
=119(x^6+x^4)/(10√3*(x^7+x^3))
=119x^5(x+1/x)/(10√3x^5(x^2+1/x^2))
=119*3/(10√3*11)
=119√3/110