Question

Find the indicated sum. 10 ∑ (2j+8) j=1

Answer 1

Answer: 190

Split the summation into smaller summations that fit the summation rules

10∑ j=1 (2j+8) = 2 10∑ j=1 (j) + 10 ∑ j=1 (8)

Firstly Evaluate

10

2 ∑ j=1 j

The formula for the summation of a polynomial with degree one is:

n∑ k=1  k =n (n+1) / 2

putting the values

2∑ j=1 j = (2)* 10 * (10+1) / 2

             = 110…………………..(1)

second Evaluate :

10 ∑ j=1 (8)

The formula for the summation of a constant is:

N  ∑ k=1 c  =  cn

Putting the values

10 ∑ j=1 (8) = 8 * 10

                   = 80……………….(2)

Adding both (1) and (2)

110+80

190