keety0305
幼苗
共回答了16个问题采纳率:87.5% 举报
x²=(4-√7)²/9
=(23-8√7)/9
1/x²=9/(23-8√7)
=9(23+8√7)/[(23+8√7)(23-8√7)]
=9(23+8√7)/[23²-(8√7)²]
=9(23+8√7)/81
=(23+8√7)/9
(x^4+x²+1)/x²=x²+1+(1/x²)
=x²+(1/x²)+1
=(23-8√7)/9+(23+8√7)/9+1
=46/9+1
=55/9
x²/(x^4+x²+1)=9/55
1年前
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