math 20-1 queation

Question

show how to use a formula to find s20 for the arithmetic series 2+4+6+....

Answer 1

The arithmetic series is 2 + 4 + 6 + ....

Common difference d = t₂ - t₁  

In the above sequence common difference d  = 4 - 2 = 2.

First term a  = 2

Formula for the sum in arithmetic series.

In this case n  = 20, a  = 2, d  = 2.