Question

If 18,a, b,-3 are in AP, then a+b is equal to​

Answer 1

a + b = 15

Explanation:

The common difference d between consecutive terms is

d = a₂ - a₁ = a - 18

d = a₄ - a₃ = - 3 - b

Thus

a - 18 = - 3 - b ( add b to both sides )

a + b - 18 = - 3 ( add 18 to both sides )

a + b = 15