Question

Find the sum of the given arithmetic series.

25 + 18 + 11 + 4 + ... + (–38)

Answer 1

so do you understand what is "d" ? (the difference between two terms)

Answer 2

any way ..
d = -7
a1 = 25 , an = -38
Im going to use this formula for sum : n(a1+an)/2
now we need to find "n"
25 - 7(n-1) = -38 -> n = 10
so:
10 * (25 - 38) / 2 = -65

Answer 3

you have earned a spot in the halls of Valhalla for this answer.

Answer 4

and i earned a warning LOL they say i should let you do something by yourself or something

Answer 5

whaaat? i help people without making them do **it all the time.