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Singleandreea
a fost răspuns

S2=1+2+3+...+10=
S3=1+2+3+...+50=
S4=1+2+3+...+75=
S5=1+2+3+...+2020=​

Răspuns :

CosmoteRo

Răspuns:

S2=(10x11):2=55

S3=(50x51):2=1275

S4=(75x76):2=2850

S5=(2020x2021):2=2.041.210

Explicație:

Maddutz

Răspuns:

suma lui Gauss : n × ( n + 1 ) : 2

S2 = 10 × (10+1) : 2= 10× 11 : 2 = 110 :2 =55

S3 = 50× ( 1+ 50) : 2= 50× 51 : 2 = 2550 : 2=1275

S4 = 75 × (1 + 75) :2 =75 ×76 :2 =5700 :2 =2850

S5 = 2020 ×(1+2020) :2= 2020×2021:2=4.082.420 :2 =22.041.210