■平方根と連分数(その36)

α=[a0:a1,a2,・・・]

λ=[an+1:an+2,an+3,・・・]+[0:an,an-1,・・・,a1]

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α=Φのとき

λ>[1:1,1,1,・・・]+[0:1,1,1,・・・,1]→φ+φ-1=√5

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α=1+√2のとき

λ>[2:2,2,2,・・・]+[0:2,2,2,・・・,2]→1+√2+√2-1=√8

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α=(3+√13)/2のとき

λ>[3:3,3,3,・・・]+[0:3,3,3,・・・,3]→(3+√13)/2+(-3+√13)/2=√13

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α=(9+√221)/10=[2:2,1,1,2,2,1,1,・・・]のとき

λ>[2:2,1,1,2,2,1,1,・・・]+[0:1,1,2,2,1,1,2,2,・・・,2]→(9+√221)/10+(-9+√221)/10=√221/5

x=[2:2,1,1,2,2,1,1,・・・]

y=[0:1,1,2,2,1,1,2,2,・・・]=1/(1+1/(1+1/x))=1/(1+1/(x+1)/x)=1/(1+x/(x+1))=(x+1)/(2x+1)=(-9+√221)/10

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α=(√3)=[1:1,2,1,2,1,2,・・・]のとき

λ>[2:1,2,1,2,・・・]+[0:1,2,1,2,・・・,1]→1+(√3)-1+√3=√12

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α=[n:1,n,1,n,1,n,・・・]のとき

x=n+1/(1+1/x)

x=n+x/(x+1)={(n+1)x+n}/(x+1)

x^2-nx-n=0 x={n+(n^2+4n)^1/2}/2

n=1のとき、{1+(5)^1/2}/2

n=2のとき、{2+(12)^1/2}/2=1+√3

n=3のとき、{3+(21)^1/2}/2

n=4のとき、{4+(32)^1/2}/2=2+2√2

n=5のとき、{5+(45)^1/2}/2

n=6のとき、{6+(60)^1/2}/2

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