若(x^2+1)/x=3,则(x^3+1/x^3+32)/(x^4+1/x^4+3)=( )。
来源:百度知道 编辑:UC知道 时间:2024/05/04 19:29:35
(x^2+1)/x=3
x+1/x=3
x^2+1/x^2=(x+1/x)^2-2=7
x^3+1/x^3=(x+1/x)(x^2-1+1/x^2)=3*6=18
x^4+1/x^4=(x^2+1/x^2)^2-2=47
(x^3+1/x^3+32)/(x^4+1/x^4+3)
=(18+32)/(47+3)
=50/50=1
(x^2+1)/x=3
x+(1/x)=3
(x^3+1/x^3+32)/(x^4+1/x^4+3)
={[x+(1/x)][x^2-x*(1/x)+(1/x^2)]+32}/{[x^2+(1/x^2)]^2-2*x^4*(1/x^4)+3}
=<3*{[x+(1/x)]^2-3x*(1/x)}+32>/<{[x+(1/x)]^2-2x*(1/x)}^2-2+3>
=[3*(3^2-3)+32]/[(3^2-2)^2+1]
=50/50
=1
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