Réponse:
A = 43/45
B = -1/2
C = -500/525
D = 4/9
Explications étape par étape:
A = 5/9 + 2/5
= (5×5)/(9×5) + (2×9)/(5×9)
= 25/45 + 18/45
= (25 + 18)/45
= 43/45
B = 1/6 - 2/3
= (1×2)/(6×2) - (2×4)/(3×4)
= 2/12 - 8/12
= (2-8)/12
= -6/12
= -1/2
C = -17/35 - 7/15
= (-17×15)/(35×15) - (7×35)/(15×35)
= -255/525 - 245/525
= (-255-245)/525
= -500/525
D = 3/4 - 7/12 + 5/18
= (3×9)/(4×9) - (7×3)/(12×3) + (5×2)/(18×2)
= 27/36 - 21/36 + 10/36
= (27-21+10)/36
= 16/3
= 4/9
