Question
An arithmetic progression has 2 as its first term. find its common difference if the sum of 33 terms is equal to six times the sum of 13 terms
Answers
Reiny
Sum(33) = 6Sum(13)
(33/2)(2a + 32d) = 6(13/2)(2a + 12d)
but a = 2
33(4 + 32d) = 78(4 + 12d)
sove for d
(33/2)(2a + 32d) = 6(13/2)(2a + 12d)
but a = 2
33(4 + 32d) = 78(4 + 12d)
sove for d