Question

if 18,x,y,-3 are in A P then the value of x+y is​

Answer 1

The value of (x + y) is equal to "15".

Step-by-step explanation:

The given series 18, x, y, -3 are in A P.

∵ x - 18 = y - x = - 3 - y = Common difference(d)

∴ x - 18 = y - x

⇒ 2x = y + 18

∴ x = $\dfrac{y + 18}{2}$      ....(1)

Also,

y - x = - 3 - y

⇒ 2y = x - 3                                        ....(2)

From (1) and (2), we get

2y = $\dfrac{y + 18}{2}$  - 3

⇒ 2y = $\dfrac{y + 18 - 6}{2}$  

⇒  4y = y + 12

⇒  3y = 12

∴ y = 4

Put y = 4 in (1), we get

x = 11

∴ x + y = 11 + 4 = 15

Hence, the value of (x + y) is equal to "15".