Question

if the 3rd and the 9th terms of an AP are 4 and -8 , which term of this AP is zero ?​

Answer 1

Answer:ans is 5

Step-by-step explanation:

Answer 2

Given: The 3rd and 9th terms of an AP are 4 and -8.

To find: The term in the AP that equates to 0.

Answer:

According to the question,

a + 2d = 4 and a + 8d = -8.

On solving, we get d (common difference) = -2 and a = 8.

Now, we have to find the term of the AP that equates to 0.

Assuming  $\tt a_n$  = 0,

$\tt 0\ =\ a\ +\ (n\ -\ 1)d$

Using the values we have above,

$\tt 0\ =\ 8\ +\ (n\ -\ 1)(-2)\\\\\\-8\ =\ -2n\ +\ 2\\\\\\-10\ =\ -2n\\\\\\\dfrac{-10}{-2}\ =\ n$

5 = n

Therefore, the 5th term of the AP equates to 0.