Răspuns:
Explicație pas cu pas:
4/21 + 5/7 =
-> cel mai mic multiplu comun al numitorilor 21 si 7 = 3x7= 21
-> amplific fractia 5/7 cu 3
= 4/21 + (5×3)/(7×3) =
= 4/21 + 15/21 =
= (4+15)/21 =
= 19/21
_____________________________________________
4/9 + 1/4 =
-> c.m.m.m.c al numitorilor 9 si 4 = 9×4 = 36
-> amplific fractia 4/9 cu 4, iar fractia 1/4 cu 9
= (4×4)/(4×9) + (9×1)/(9×4) =
= 16/36 + 9/36 =
= (16+9)/36 =
= 25/36
____________________________________
5/10 + 3/6
5/10 = (5:5)/(10:5) = 1/2 → am simplificat fractia cu 5
3/6 = (3:3)/(6:3) = 1/2 → am simplificat fractia 3/6 prin 3, impartind atat numaratorul, cat si numitorul cu 3
5/10 + 3/6 = 1/2 + 1/2 = 2/2 = 1
______________________________________________________
1/2 + 3/5
→ c.m.m.m.c al numitorilor 2 si 5 = 2×5 = 10
→ aduc fractiile la acelasi numitor, amplificand fractia 1/2 cu 5, iar fractia 3/5 cu 2
= ( 1×5)/(2×5) + (3×2)/(5×2) =
= 5/10 + 6/10 =
= (5+6)/10 =
= 11/10
