Question

Find the number of terms in the A P ,18 ,15. 1/2 , 13 ........... , -47 .

Answer 1

Answer:

No. of Terms = 27

Step-by-step explanation:

Given A.P = 18, 15¹/₂, 13,..........,-47

∴a₁=18            ∴aₙ=-47           ∴d=-2¹/₂             ∴n=?

⇒ aₙ = a + (n-1) d

⇒ -47 = 18 + (n-1) x -2¹/₂

⇒ -47 - 18 = -2¹/₂ x (n-1)

⇒ -65 / -2¹/₂ = n - 1

⇒ 26 + 1 = n

⇒ 27 = n