Problem 737

Find the sum of the first five terms of the arithmetic series:

a_n = 2n +2.

 

Solution:-

 

Find a₁ and  a₅  and use the formula for the sum of an arithmetic series:    S_n = (a₁ + a_n)

a₁ = 2* 1 + 2 = 4

a₅ =2*5 +2 = 12

S_n = 40