Question

What is the sum of the finite arithmetic series? (-10)+0+10+20+....+30

Answer 1

We have been given a finite arithmetic series:

$(-10)+0+10+20+30$

The given series has 5 terms, which means $n=5$

The first term of the series is : $t_1=-10$

and the last term of the series is: $t_n=30$

The sum of the finite arithmetic series is given by:

$S=n \times \frac{(t_1+t_n)}{2} =5 \times \frac{(-10+30)}{2} =5 \times \frac{20}{2} =5\times 10=50$

So the sum of the given finite arithmetic series is 50.

Answer 2

I think the finite arithmetic series meant to be:

(-10)+0+10+20+...+130

So to that the answer would be:

900