Question
What is the sum of the geometric series 20 + 21 + 22 + 23 + 24 + … + 29?
Answers
Damon
https://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html
a= 20
d = 1
or just figure it out
say it was just 20, 21, 22, 23
the number of terms is 1+ 23-20 = 4
the average is 21.5
4*21.5 = 86
check --- sure enough 86
so now this hard one 20,21 .... 29 number of terms = 1 + 29 -20 = 10
average = 49/2 = 24.5
so 10 * 24.5 = 245
a= 20
d = 1
or just figure it out
say it was just 20, 21, 22, 23
the number of terms is 1+ 23-20 = 4
the average is 21.5
4*21.5 = 86
check --- sure enough 86
so now this hard one 20,21 .... 29 number of terms = 1 + 29 -20 = 10
average = 49/2 = 24.5
so 10 * 24.5 = 245