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4楼
发表于 2012-8-26 18:59
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本帖最后由 ys1937 于 2012-8-26 19:02 编辑
X + Y = [3^(1/2) - 2^(1/2)]/[3^(1/2) + 2^(1/2)] + [3^(1/2) + 2^(1/2)]/[3^(1/2) - 2^(1/2)]
= {[3^(1/2) - 2^(1/2)]^2 + [3^(1/2) + 2^(1/2)]^2} //[3^(1/2) + 2^(1/2)][3^(1/2) - 2^(1/2)]
= 10
X * Y = 1
X^3 + Y^3
= (X + Y)(X^2 - XY + Y^2)
= (X + Y)[(X + Y)^2 - 3XY]
= 10 * [100 -3]
= 970
二种解法,你都得改写成根号、指数形式,读起来才方便。 |
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