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.

Answer 1

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) = ...