Find S25 for (-7) + (-2) + 3 + 8 +...

A. 1,320
B. 1,325
C. 825
D. 820
I think A

I got 1325 or B)

Sum(25) = (25/2)( -14 + 24(5))
= (25/2)(106) = 1325

8 es el 25%de

To find the sum of an arithmetic series, you can use the formula: Sn = (n/2)(a1 + an), where Sn represents the sum of the first n terms, a1 is the first term, and an is the last term.

In this case, the given series is (-7) + (-2) + 3 + 8 + ... and we need to find S25, the sum of the first 25 terms.

We can see that the series is an arithmetic series with a common difference of 5, starting from -7. To find the last term, we can use the formula: an = a1 + (n - 1)d, where a1 is the first term, n is the number of terms (in this case, 25), and d is the common difference.

Using the formula, we find that the last term is -7 + (25 - 1) * 5 = -7 + 24 * 5 = -7 + 120 = 113.

Now that we have the first term (a1 = -7), the last term (an = 113), and the number of terms (n = 25), we can use the sum of arithmetic series formula to find S25:

S25 = (25/2)(-7 + 113)
= (25/2)(106)
= 25 * 53
= 1325

Therefore, the sum S25 for the given series is 1,325.

So the correct answer is B. 1,325.