Question

If 10th term of an A.P is 15 and the 15th term is 10, find the series?​

Answer 1

Answer :

a + 9d = 15 ( eq 1 )

a + 14d = 10 ( eq 2)

By subtracting eq 1 and 2

a + 9d - a - 14d = 15 - 10

9d - 14d = 5

-5d = 5

d = -1

a = 24

Answer 2

a10=15

a+9d=15....(1)

a15=10

a+14d=10.....(2)

subtract (2) from(1)

5d=-5

d=(-1)

put the value in equation (1)

a+9(-1)=15

a-9=15

a=15+9

a=24

Difference in AP series is equal

a=24

a+d=a2 .....(24-1)=(23)=a2

hence

AP series will be

24,23,22,21...................

Hope its helpful to you ☺️