Resposta :
Denominadores diferentes precisa tirar o mmc.
3 , 2 , 4 / 2
3 , 1 , 2 / 2 mmc = 2 . 2 . 3 = 12
3 , 1 , 1 / 3
1 , 1 , 1
[tex]\frac{2}{3} - \frac{1}{2} + (-\frac{1}{4} ) =\\\\\frac{8-6-3}{12} = - \frac{1}{12}[/tex]
Denominadores diferentes precisa tirar o mmc.
3 , 2 , 4 / 2
3 , 1 , 2 / 2 mmc = 2 . 2 . 3 = 12
3 , 1 , 1 / 3
1 , 1 , 1
[tex]\frac{2}{3} - \frac{1}{2} + (-\frac{1}{4} ) =\\\\\frac{8-6-3}{12} = - \frac{1}{12}[/tex]