+73 4) For the sum -10 -13 -16 -... -43:
(a) Rewrite the sum using summation notation (\(\sum\)).
(b) Evaluate the sum.
+128460 (a)
12
∑ -7 - 3n
n = 1
Note that other forms are possible.....
(b) The sum can be found as
[ First Term + Last Term ] * [ Number of terms] / 2
The number of terms is [ 43 - 10 ] / 3 + 1 = 33/3 + 1 = 11 + 1 = 12
So....the sum is
[ -10 + -43 ] * [ 12 / 2] =
] -53] * 6 =
-318
