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mathquark
Joined: 02 Oct 2004Posts: 16
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Posted: Fri Jan 21, 2005 3:54 am Post subject: two questions
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1)x^a=2, x^(-b)=3 then find x^(a^2-b^2)=?
2)Let z be a complex number.If |z+(1/z)|=3 then find the minumum and maximum value of |z|
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Kenny TM~
Frequent VisitorJoined: 20 Jan 2004Posts: 141
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Posted: Fri Jan 21, 2005 11:37 am Post subject: Re: two questions
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mathquark wrote:
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| 1)x^a=2, x^(-b)=3 then find x^(a^2-b^2)=?
2)Let z be a complex number.If |z+(1/z)|=3 then find the minumum and maximum value of |z|
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1)
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Andy
Frequent VisitorJoined: 28 Oct 2003Posts: 459
Location: Hong Kong
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Posted: Sat Jan 22, 2005 5:58 pm Post subject: Re: two questions
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mathquark wrote:
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| 2)Let z be a complex number.If |z+(1/z)|=3 then find the minumum and maximum value of |z| |
If we write , then we have .
Therefore, we have . It gives .
In fact, if we set , the equality is achieved. Therefore, the maximum value of z is .
_________________
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