1.

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

Answer»

Answer:

Let d be the common difference

a - 18 = d_{1}

B - a = d_{<klux>2</klux>}

- 3 - b = d_{3}

As we KNOW that the d is same throughout the AP

So we can say that

d_{1} = d_{2} = d_{3}

putting the VALUES of d_{1} & d_{2}

a - 18 = b - a

b = 2a - 1 8

now putting the value of d_{2} & d_{3}

b - a = -3 -b

2b -a = 18 - 3

2( 2a - 18) - a = 15

4a - a = 15 + 36

3a = 51

a = 17

b = 2a - 18

b = 2(17) - 18

b = 34 -18

b = 16

finding a + b

= 17 + 16

= 33


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