Question

if 21,a,b,-3are in a p then find the value of (a plus b)

Answer 1

21,a,b,-3 are in a p then we need to determine the common difference d


-3 is the 4th term

4th term = a + 3d

         -3  = 21 + 3d



            3d = -24

              d = -8


2nd term, a = 21 - 8 = 13

3rd term, b = 13 - 8 = 5


a + b = 13 + 5 = 18

Answer 2

Answer:

Step-by-step explanation:

21,a,b,-3 are in a p then we need to determine the common difference d

-3 is the 4th term

4th term = a + 3d

-3 = 21 + 3d

3d = -24

d = -8

2nd term, a = 21 - 8 = 13

3rd term, b = 13 - 8 = 5

a + b = 13 + 5 = 18