Question

Comparati numerele a= 2 + 4 + 6 + 8 +.... + 100 si b = 3 + 6 + 9 + 12 +... + 120

Answer 1

Explicație pas cu pas:

A) 2+4+6+8+....+100 = 2×1+2×2+2×3 +2 ×4 +......... 2×50 =

2×( 1+2+3+4+.....+50). = [(50+1) ×( 50-1+1):2] ×2 =

51 x 50 = 2.550

2.550 :2 = 1275

1275 x 2 = 2550