Question

In the following APs find the missing term in the box:

`square, 13, square, 3`

Answer 1

18, 13, 8, 3

Explanation:

For this A.P.,

a₂ = 13 and

a₄ = 3

We know that, a_n = a + (n − 1) d

a₂ = a + (2 − 1) d

13 = a + d                ...(I)

a₄ = a + (4 − 1) d

3 = a + 3d               ...(II)

On subtracting (I) from (II), we obtain

−10 = 2d

d = −5

From equation (I), we obtain

13 = a + (−5)

a = 18

a₃ = 18 + (3 − 1) (−5)

= 18 + 2 (−5)

= 18 − 10

a₃ = 8

Therefore, the missing terms are 18 and 8 respectively.