Use the Formula for the Sum of the First n Terms of an Arithmetic Sequence
-Find 2 + 4 + 6 + 8 + . . ., the sum of the first 45 positive even integers.
A) 2070
B) 2074
C) 2024
D) 2020

Question

Quizplus · Accepted Answer

The sum of the first n terms of an arithmetic sequence can be found using the formula $S_n = \frac{n}{2}(a_1 + a_n)$, where $S_n$ is the sum of the first n terms, $a_1$ is the first term, $a_n$ is the nth term, and n is the number of terms. For the first 45 positive even integers, $a_1 = 2$, $n = 45$, and $a_n = 2n = 90$. Plugging these values into the formula gives $S_{45} = \frac{45}{2}(2 + 90) = \frac{45}{2}(92) = 2070$.

Use the Formula for the Sum of the First N