Question

If 18, a, b, −3 are in A.P., the a + b =
(a) 19
(b) 7
(c) 11
(d) 15

Answer 1

Answer:

The value if a + b is 15.

Among the given options option (d) 15 is a correct answer.

Step-by-step explanation:

Given :  

18, a, b, –3 are in A.P

Let a1 =  18 , a2 = a  , a3 = b , a4 =  -3  

If terms are in A.P, then common difference (d) of any two consecutive terms is same.  

a2 - a1 = a4 - a3

a– 18 = - 3  – b

a + b = - 3 + 18

a + b = 15

Hence, the value if a + b is 15.

HOPE THIS ANSWER WILL HELP YOU….

Answer 2

GIVEN:

AP = 18, a, b, -3.....

First-term = 18

We know that,

In an AP, the common difference between the terms is the same.

Common Difference = a2 - a1

=> a - 18 = -3 - b

=> a + b = -3 + 18

=> a + b = 15

Therefore, a + b = 15