Question

s=1+2+3+5+...55
s=1+2+3+5+...123​

Answer 1

Răspuns:

1+2+3+3+...55=55×(55+1):2=55×56:2=55×28=1540

1+2+3+5+...123=123×(123+1)=123×124:2=123×62=7626

Explicație pas cu pas:

.......succes!.