Question

e) 40 + 41 + 42 + ... + 80 =
25 + 26 + 27 + ... + 120 =
2 + 3 + 4 + 5 + ... + 48 =

Urgent​

Answer 1

40 + 41 + 42 + ... + 80 =

n= (80 – 40) + 1 = 41 termeni

S= 41(40 + 80) / 2= 2460

25 + 26 + 27 + ... + 120 =

n = 120 - 25 + 1 = 96 termeni

S = 96(25 + 120) / 2

S = 6960

2 + 3 + 4 + 5 + ... + 48 =

n = 48 - 2 + 1 = 47 termeni

S = 47(2 + 48) / 2

S = 1175