Salut :)
Réponse :
a ) 3x / 2 + x / 4
= 6x / 4 + x / 4
= 7x / 4
b ) 5x / 6 + ( x - 4 ) / 3
= 5x / 6 + ( 2x - 8 ) / 6
= ( 5x + 2x - 8 ) / 6
= ( 7x - 8 ) / 6
c ) 3 + ( x - 1 ) / 5
= 15 / 5 + ( x - 1 ) / 5
= ( 15 + x - 1 ) / 5
= ( 14 + x ) / 5
d ) - 5x - ( 3x - 2 ) / 4 + 3
= - 20x / 4 - ( 3x - 2 ) / 4 + 12 / 4
= ( - 20x - 3x + 2 + 12 ) / 4
= ( -23x + 14 ) / 4
Voilà :)
