Răspuns :
Răspuns:
S=2+4+6+.....+102
S=2( 1+2+3+..+51)
S= 2×\frac{51*52}{2}
2
51∗52
S=2×\frac{2652}{2}
2
2652
S=2×1326
S=2652
5(1+2+34+...50+)=5X50/2=6375
Răspuns:
2+4+6+....+102=(102+2) x [(102-2):2+1]:2=52 x 51 = 2652
5+10+15+...+250=(250+5) x [(250-5):5+1]:2 = 255x25=6375
1+4+7+...+235=(235+1)x{(235-1):3+1]:2=119x79=9401