Question

If 18,a, b, -3 are in ap then find a plus b

Answer 1

Answer:

as 18,a,b,-3 are in ap

so

a-18=b-a= -3-b

=> a-18=b-a

=> a+a-b=18

=> 2a-b=18

=> 2a=18+b

again,

b-a= -3-b

=> b+b-a= -3

=> 2b-a= -3

=> 4b-2a= -6

=> 4b-(18+b)= -6

=> 4b-18-b= -6

=> 3b=18-6

=> 3b=12

=> a=12/3

=> a=4

2a=18+b

=> 2.4=18+b

=> 8=18+b

=> b=8-18=. -10

so,

a+b

=4+(-10)

=4-10

= -6