fifteenth term is –7 -----> a+14d = -7 **
the sum of the first fifteen terms is 210
----> (15/2)(2a + 14d) = 210
2a + 14d = 28 ***
subtract ** from ***
a = 35
back in **,
a + 14d = -7
35+14d = -7
d = -3
Now form the first 3 terms
Find the first three terms of an arithmetic series in which the fifteenth term is –7 and the sum of the first fifteen terms is 210
2 answers
what is the equation??