There are a couple of ways to approach this evaluation, but one common method is to use the formula for the sum of an arithmetic series:
Sn = n/2(a1 + an)
where Sn is the sum of the first n terms, a1 is the first term, an is the nth term, and n is the number of terms.
In this case, we are summing the expression 16(5r - 1) from r = 1 to r = n. So we can plug in a1 = 16(5(1) - 1) = 64, an = 16(5n - 1), and n = 1:
S1 = 1/2(64 + 16(5(1) - 1)) = 40
Therefore, σ𝑟=1 16(5𝑟 − 1) = 40.
Evaluate σ𝑟=1
16 (5𝑟 − 1)
1 answer
1 answer