Asked by Aaradhya

the fourth term of an ap is 11 And the eight term exceeds twice the fourth term by 5.find the ap and sum of first 20 terms.
Answered by Steve
T4 = 11
T8 = 2*11+5 = 27
so, T8-T4 = 4d = 16
d = 4
a+3d = 11, so a = -1

S20 = 20/2 (2a+19d) = ...