题库搜索>问题求解PS-13124
If x ≠ 0, then (x + 1/x)2 - (x - 1/x)2 =
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平方差公式a^2-b^2=(a+b)(a-b)
化解原式=（x+1/x+x-1/x)*(x+1/x-x+1/x)=2x*2/x=4
lgw273862
可是（x+1/x+x-1/x)不是等于2吗，那算出来不应该是4/x
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2022-05-14 15:19:49
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