JEE Main 2019 Mathematics question
If are in A.P. such that , then the sum of the first 15 terms of this A.P. is:
Answer: (D)
Solution
3(a + 7d) = 40 and S = 15(a + 7d).
If are in A.P. such that , then the sum of the first 15 terms of this A.P. is:
3(a + 7d) = 40 and S = 15(a + 7d).