The Total solution for NCERT class 6-12
If the sum of n terms of an A.P. is 3n2 +5n and its mth term is 164, find the value of m.
Let’s consider a and b tobe the first term and the common difference of the A.P. respectively.
am = a + (m –1)d = 164 … (1)
We the sum of theterms is given by,
Sn =n/2 [2a + (n-1)d]