Question

Find the A.P whose third term is 5 and seventh term is 9.

Answer 1

Answer:

Step-by-step explanation:

Let the first term be a and common difference be d.

∴Third term = a + 2d = 5........(i)

Seventh term = a + 6d = 9........(ii)

(ii) - (i)⇒ a+ 6d - a - 2d = 9 - 5

⇒4d = 4

⇒d = 1

∴Putting d = 1 in (i) ⇒ a + (2×1) = 5

⇒a + 2 = 5

⇒a = 3

∴The A.P. = a , a + d , a + 2d ,.............so on

⇒3 , (3+1) , (3 + 1 + 1)..........so on

⇒3 , 4 , 5,........so on

Hence , the A.P. = 3 , 4, 5 ,......