Question

the sixth term of an ap is zero prove that the 21st term is triple at the 11th term

Answer 1

Answer:

Step-by-step explanation:

t6=a+(6-1)d

=a+5d

But,

t 6 is also = 0

Therefore,

a+ 5 d= 0

a= -5d

now,

t11= a+10d

=-5d + 10d

= 5d

t21= a+ 20d

= -5d + 20d

= 15d

= 3 X 5d

=3X t11