Question

If 18,a,b,-3are in AP then a+b is equal to

Answer 1

The value of  (a + b) is "15".

Step-by-step explanation:

we heve,

18, a, b, - 3 are in AP.

∴ $a - 18= b - a = - 3 -b$

⇒ $a - 18 = b - a$      

⇒ 2a -b = 18                             ....(1)

and$b - a = - 3 - b$  

⇒ - a + 2b = -3                         ....(2)

Multiply (1) × 2 and (2) adding, we get

3a = 33

⇒ a = 11

Putting a = 11 in (1), we get

2 × 11 - b = 18        

⇒b = 22 - 18 = 4

∴ a + b = 11 + 4 = 15

Hence, the value of  (a + b) is "15".