Question

If 18,a,b,-3 are in arithmetic progression then a+b=​

Answer 1

Answer:

a + b = 15

Step-by-step explanation:

Given that: 18, a, b, -3 are in AP.

⇒ a - 18 = b - a = -3 - b   [ Common difference is same in an AP ]

⇒ a - 18 = -3 - b

⇒ a + b = 18 - 3

⇒ a + b = 15   ... ( 1 )

Similarly,

⇒ b - a = - 3 - b

⇒ 2b - a = -3  ... ( 2 )

Adding ( 1 ) and ( 2 ) we get,

⇒ a + b + 2b - a = 15 - 3

⇒ 3b = 12

⇒ b = 12/3 = 4

Hence the value of b is 4.

⇒ a = 15 - b

⇒ a = 15 - 4 = 11

Therefore ( a + b ) = 15 where, a = 11 and b = 4.