Question

Find the sum if the first 80 even integers beginning with -78

Will mark

Answer 1

162

Explanation:

sum (n=-39) (to 41) of (2n) = 162

It won't let me put in a picture, but that is the formula I used.

-39 is one half -78, because I'm using 2n

41 = -39 + 80

2n is so we only get even numbers