Question

in an ap given a=10, d=4, nth term is 38 then find n and Sn​

Answer 1

Step-by-step explanation:

a=10 d=4 Tn=38

Tn=a+(n-1)d

=>38=10+(n-1)4

=>38=10+4n-4

=>4n+6=38

=>4n=32

=>n=8

Sn=n/2{2a+(n-1)d}

=8/2{2×10+(8-1)4}

=4(20+28)

=4×48

=192