Question

if 5 times of 21st term of an ap is equal to its 5th term show that 25th term is zero

Answer 1

let a be the frst trm and d be common difference
t21 =a+20d
fifth term=a+4d
accor to ques
5(a+20d)=a+4d
5a+100d = a+4d
5a-a= 4d-100d
4a= 96d