Réponse :
Explications étape par étape
Bonjour
a) 4/5 + -5/2 - (-2/3+ -3/4)
= 4/5 - 5/2 + 2/3 + 3/4
= (4 x 12)/(5 x 12) - (5 x 30)/(2 x 30) + (2 x 20)/(3 x 20) + (3 x 15)/(4 x 15)
= 48/60 - 150/60 + 40/60 + 45/60
= (48 + 40 + 45 - 150)/60
= (133 - 150)/60
= (-17)/60
b) -2/3 -(4/5- (-3/4- -5/2)
= -2/3 - (4/5 + 3/4 - 5/2)
= -2/3 - 4/5 - 3/4 + 5/2
= (-2 x 20)/(3 x 20) - (4 x 12)/(5 x 12) - (3 x 15)/(4 x 15) + (5 x 30)/(2 x 30)
= -40/60 - 48/60 - 45/60 + 150/60
= (-40 - 48 - 45 + 150)/60
= 17/60
c) - (-2/3- -5/2) -( 4/5- -5/2)
= 2/3 - 5/2 - 4/5 - 5/2
= 40/60 - 150/60 - 48/60 - 150/60
= (40 - 150 - 48 - 150)60
= (40 - 348)/60
= (-308/60)
= (-77 x 4)/(4 x 15)
= (-77/15)