a^(1/2)+a(-1/2)=x^(1/2)
[a^(1/2)+a(-1/2)]^2=x
a+1/a+2=x
a+1/a=x-2
所以:
[x-2+√(x^2-4x)]/[x-2-√(x^2-4x)]
={x-2+√[(x-2)^2-4]}/{x-2-√[(x-2)^2-4]}
={x-2+√[(x-2)^2-4]}/{x-2-√[(x-2)^2-4]}
={(a+1/a)+√[(a+1/a)^2-4]}/{(a+1/a)+√[(a+1/a)^2-4]}
={(a+1/a)+√(a-1/a)^2}/{(a+1/a)+√(a-1/a)^2}
={(a+1/a)+|a-1/a|}/{(a+1/a)+|a-1/a|}
因為a>1,所以:a-1/a>0,即|a-1/a|=a-1/a
={(a+1/a)+a-1/a}/{(a+1/a)+a-1/a}
=(2a)/(2/a)
=a^2
若a^(1/2)+a(-1/2)=x^(1/2) (a>1), 求x-2+根號下(x^2-4x)除以x-2-根號下(x^2-4x)
若a^(1/2)+a(-1/2)=x^(1/2) (a>1), 求x-2+根號下(x^2-4x)除以x-2-根號下(x^2-4x)
數(shù)學人氣:123 ℃時間:2020-05-14 10:35:31
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