Question

If the 4th term of an ap is 0,then prove that 25th term =3 times its 11th term

Answer 1

an= a+(n-1)d
an= a+(4-1)d
0=a+3d
a= (-3d)
since,
25th term=>
a+(n-1)d
-3d+(24d)
21d
then,
11th term=》
3{a+(n-1)d}
3{-3d+10d}
3{7d}
21d
since 25 th term is equal to 3 times 11th term
hence proved.