Question

If 18,a,b,-3 are in AP find a+b

Answer 1

Answer:

Step-by-step explanation:

first term = 18

d1=a-18,

d2=b-a,

d3=-3-b.

d1=d2,

a-18=b-a

2a=b+18

a=(b+18)/2..............................(i)

d2=d3

b-a=3-b

2b=3+a

from (i)

2b=3+(b+18)/2

2b=(6+b+18)/2

4b=b+24

3b=24

b=8

now,

a=(b+18)/2

a=(8+18)/2

a=26/2

a=13.