Question

If 21, a,b, - 3 are in A.P then find the value of (a+b) ?

Answer 1

Answer:

a+b = 18

Step-by-step explanation:

In AP

sum of 1st term and last term is equal to sum of 2nd term and second from last term

a1, a2, a3........an-1, an

then

a1+an= a2+an-1

21+(-3)= a+b

a+b= 18

Answer 2

21,a,b,-3 are ap

a-21=d

-3-b=d

21+3d=-3

3d=-24

d=-8

a-21=-8

a=13

-3-b=-8

-b=-5

b=5

a+b=13+5

=18