Question

if 18,x,y,-3 are in arithmetic progression then the value of x + y is..​

Answer 1

Answer:

since 18, x, y, - 3 are in AP.

a = 18

n = 4

4th term = - 3

a + (4 - 1)d = - 3

a + 3d = - 3

18 + 3d = - 3

3d = - 21

d = - 7

so x = 18 - 7 = 11

y = 11 - 7 = 4

Answer 2

Answer:

let p be the first term i,e;18

and d be the common difference

from given series

=> 4th term=p+3d=-5

by using formula

a4-a1

4 - 1

=> -5-18. =. -21

3 3

1. =>d=-7

by given arithmetic progression,

a,a+d, a+2d ,a+3d ----

=>. x=18+(-7)=18-7=11

=>. x=11

=>. y= 18+2(-7)=18-14=4

=>. y=4

=> by the given condition

( x+y)

=>. (11+4)=. 15