Respostas

2014-06-07T18:01:27-03:00
1) 1/2xy-2xy => (2xy)⁻¹ - 2xy => 2xy[(2xy)⁻² - 1] 
.............
 2) -3/5x+7/2x-15/4x, mmc (2x, 4x, 5x) = 20x
 
 -3/5x+7/2x-15/4x = (-12+70-75)/20x = -17/20x
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