once is enough, but what the heck?
the common difference is d = (7 1/2 + 5)/5 = ____
a = -5 - 9d = ___
S20 = 20/2 (2a+19d) = ___
The 10th and 15th terms of an AP are -5 and -7 1/2 respectively.What is the sum of the first 20 terms?[WAEC]
3 answers
The first term of an AP is 6 and the fifth term is 18. Find the number of terms in the series having a sum of 162 solve it
Solve this:The first term of an AP is 6 and the fifth term is 18. Find the number of terms in the series having a sum of 162