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大家帮忙啊！
2009年08月08日 14点08分
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The expression is meaningful if both a and b are negative.
Since sqrt{ab} is well-defined, a nad b must be of the same sign.
However, if both a and b are positive, then the 2 sqrt{ab} must be less thaqn (a + b) and the denominator will be undefined.
Therefore both a and b are negative.
Let a =-x and b =-y ,where boh x and y are positive. Simplifying, we will get (b-a)/(a+b)
2009年08月08日 14点08分
7
Since sqrt{ab} is well-defined, a nad b must be of the same sign.
However, if both a and b are positive, then the 2 sqrt{ab} must be less thaqn (a + b) and the denominator will be undefined.
Therefore both a and b are negative.
Let a =-x and b =-y ,where boh x and y are positive. Simplifying, we will get (b-a)/(a+b)
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