Question

Determine the 25 th term of an A.P ;whose9th term is _6 and common difference 5by 4

Answer 1

a9 = 6

D = 5/4

so,

a + 8d = 6

a + 8(5/4)=6

a + 10 = 6

a = 6-10

a= -4

hence

a=-4 , d=5/4. n=25

we have to find 25th term

a+(n-1)d = an

-4+(25-1)5/4= a25

-4+ 30

a25= 26

Answer 2

given

a9 = -6

a25 =?

d= 5

a 25 = a+24 d

        = a+ 24*5 = 120

       a= -120