Question

The 6th term of an A.P. is zero. Prove that this 21st term is triple its 11th term.
t21= 3t11​

Answer 1

Step-by-step explanation:

t6=0

To prove t21=3t11

t21=t+20d

t11=t+10d

t+20d=3(t+10d)

t+20d=3t+30d

2t+10d=0

t+5d=0

t6=0.