Question

Find the sum of the first 20 terms of the sequence
4, 6, 8, 10

Answer 1

hey mate your answer is here ✌✌..(~_~)
(a )first term =4
(d)for common difference =2
for sum of first 20 terms
sn=n/2+2a+(n-1)×d
put the value
s20=20/+2×2+(20-1)×2
hence 420 is your answer

Answer 2

Given terms are related to AP.

        In the given AP,

First term = a

                 = 4

Common Difference = d

                = any term - previous term

                = 10 - 8 = 8 - 6 = 6  - 4

                = 2

We know, in AP sum of n terms is $\dfrac{n[2a+(n-1)d]}{2}$

        Substituting values  from question : -

sum of 20 terms = $\dfrac{20}{2}[2(4)+(20-1)2]$

sum of 20 terms = 10( 8 + 38 )

sum of 20 terms = 460

Therefore, sum of 20 terms of the given AP is 460.