mai intai fac sumele si pe urma bag rezultatul sub radical
1+2+3+...+200 = 200*201/2 = 100*201
Radical din 100*201 = 10 radical 201
1+3+5+...+195 =
Se aplica formula
1+3+5+...+2n-1 = n*n
2n-1=195
2n=196
n=98
Deci 1+3+5+...+195 = 98*98
Radical din 98*98 = 98
2+4+6+..+142+72 =
2(1+2+3+...+71) + 72 =
2*71*72/2 + 72 =
71*72+72 =
72(71+1) =
72*72
radical 72*72 = 72
1+2+3+...................+200-100.101
1+2+3+...+200 = 200*201/2 = 100*201
100*201-100*101 = 100(201-101) = 100*100
asadar radical din 100*100 = 100
