Question

what is the sum of the finite arithmetic series?
(-10)+0+10+20+....+130

Answer 1

n(first + last)
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2

Answer 2

in other words we can know 2 times the sum better, then divide it in half

Answer 3

The answer choices are
900
1,000
950
955

Answer 4

Can you figure out how many terms are in the sequence without using any formula?

Answer 5

what does the formula determine as an answer then?

Answer 6

icame up with at least 3 different number of terms in my head alone lol

Answer 7

A = -10 + 0 + ...+130
+A = 130 + 120 + ... - 10
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2A = 120 + 120 + .... + 120, n times

therefore A = 120n/2

Answer 8

im not quite sure which one it is...

Answer 9

10, 20 2 terms
10, 20, 30 3 terms
10, 20, 30, ...., 130 ? terms

then include the first two terms.

Answer 10

is it 900?

Answer 11

Yes.