Respostas

2014-03-04T23:13:33-03:00

 (x^-1 + y^-1)^-1 = 2

(1/x + 1/y)^-1 = 2

1/(1/x +1/y) = 2

2/x + 2/y =1

2/y = 1 - 2/x

2/y = (x -2)/x

y(x -2) = 2x

y = 2x/(x -2)

R: c)

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