Question

what is the sum of term of the series(-1)+(-2)+(-3) + + (-10)




what is the sum of the first five terms of the series 35+30+25 +



what is the sum of the last four terms of the series 7+9+11+ + 21



what is the sum of the first terms of the series 7+12+17+

Answer 1

(-1)+(-2)+(-3) + + (-10)

start by identifying the common difference of this series ?

Answer 2

use AP for the purpose...
formula that would be used here is
(n/2)(2a+(n-1)d)
where n = no. of terms
a = first term of the AP
and d = common difference

Answer 3

thank you

Answer 4

you r welcome