Question

2 ana
5. If 18, X, Y, -3 are in AP , find the value of x + y​

Answer 1

Given

18, X, Y, -3 are in AP

so, a = 18 , n=4 and a(4th) = -3

a(nth) = a + (n-1)d

a(4th)= 18 +(4-1)d=-3

               3d = -21

                 d = -7

a(2nd) = a + (2-1)d = X

             18 + 1(-7) = X      

                X = 11

a(3rd) = a+ (3-1)d = Y

           18 +2(-7)=Y

                Y =4

X + Y = 11 + 4 = 15

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