Question

Determine the arithmetic progression whose 3^rd term is 5 and 7^th term is 9.

Answer 1

For an A.P.

t₃ = 5

`=>` a + 2d = 5  ...(i)

And t₇ = 9

`=>` a + 6d = 9  ...(ii)

Subtracting (i) from (ii), we get

4d = 4

`=>` d = 1

Substituting d = 1 in (i), we get

a + 2 × 1 = 5

`=>` a = 3

Thus, the required A.P. = a, a + d, a + 2d, a + 3d, .....

= 3, 4, 5, 6, .....