(1/a+1/b)² ÷ (1/a²-1/b²) ²是平方,/是分数线
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![(1/a+1/b)² ÷ (1/a²-1/b²) ²是平方,/是分数线](/uploads/image/z/1614828-12-8.jpg?t=%281%2Fa%2B1%2Fb%29%26sup2%3B+%C3%B7+%EF%BC%881%2Fa%26sup2%3B-1%2Fb%26sup2%3B%29+%26sup2%3B%E6%98%AF%E5%B9%B3%E6%96%B9%2C%2F%E6%98%AF%E5%88%86%E6%95%B0%E7%BA%BF)
(1/a+1/b)² ÷ (1/a²-1/b²) ²是平方,/是分数线
(1/a+1/b)² ÷ (1/a²-1/b²)
²是平方,/是分数线
(1/a+1/b)² ÷ (1/a²-1/b²) ²是平方,/是分数线
就是利用平方差公式啊.x^2-y^2=(x+y)*(x-y)
(1/a+1/b)²÷(1/a²-1/b²)
=(1/a+1/b)²÷[(1/a+1/b)*(1/a-1/b)]
=(1/a+1/b)÷(1/a-1/b)
=[(a+b)/ab]÷[(a-b)/ab]
=(a+b)/(a-b)