Question
The third and eleventh term of an arithmetic progression are -15 and 25 respectively. Find the:
A.common difference
B.first term
C.number of terms that will give a sum of 30
A.common difference
B.first term
C.number of terms that will give a sum of 30
Answers
oobleck
a11-a3 = 8d = 40
now find a, and then n such that
n/2 (2a+(n-1d)) = 30
now find a, and then n such that
n/2 (2a+(n-1d)) = 30