Question

find 11th term of AP sum of n term is Sn = 2n + 3n

Answer 1

Sn= 2n+3n
put value of n=1
2(1)+3(1)=2+3=5 =a1

put value of n=2
2(2)+3(2)=4+6=10 =S2
a1+a2=S2
5+a2=10
a2=10-5
a2=5

a2-a1 = 5-5=0, d=0

a11=a+10d
5+10(0)=5+0=5