Question

How many terms of the arithmetic sequence 2 4 6 8 will give a result in the sum of 600?

• A. 23
• B. 25
• C. 24
• D. 26

Answer 1

The correct option is C 24

a = 2
d = 4 – 2 = 2

$s=\frac{n}{2}\left(2a+\left(n-1\right)d\right)600=\frac{n}{2}\left(2\times 2+\left(n-1\right)\times 2\right)1200=n\left(4+2n-2\right)1200=2n^2+2n{n}^2+n-600=0$

Solve for n
n = 24 and - 25
Therefore n = 24.