If sn=3n+5n² find 20th term

1.	If sn=3n+5n² find 20th term
Answer» n=1 S1=A1=3(1)+5(1) A1=8Similarly S2=A1+A2=26A2=26-A1=18d=A2-A1=10Now,nth term=A1+(n-1)dSo 20th term=8+(20-1)10=8+190=198 n=20 Sn=3×20+5×400 =60+2000 =2060

Discussion