Question

If the 9^th term of an A.P. be zero, then find the ratio of its 29^th and 19^th term.

• A. 1 : 2
• B. 2 : 1
• C. 1 : 3
• D. 3 : 1

Answer 1

The correct option is B

2 : 1

Given that 9^th term = a + (9 - 1) d = 0 $\Rightarrow$ a + 8d = 0
29^th term = a + (29 - 1) d = a + 28d
19^th term = a + (19 - 1) d = a + 18d
Now ratio of 29^th and 19^th terms $=\frac{a+28d}{a+18d}=\frac{(a+8d)+20d}{(a+8d)+10d}=\frac{20d}{10d}=\frac{2}{1}.$