Question

sum of 1st 20 terms of an ap is -240 and first term is 7 term. find its 24th term

Answer 1

a=7
S20=-240
-240=20/2 (14+19d)
-240*2/20=14+19d
-24-14=19d
d=-38/19
 d=2
a24=7+23*-2
       =7-46
        =  -39

Answer 2

Step-by-step explanation:         S20 = -240

     First term(a) =7

   t24=?

s20 -240

n/2[2a+(n-1)d] = -240

10[14+19d]=-240

14+19d=-24

19d=-24-14

19d=-38

d = -2

t24=a+(n-1)d

     =7+23(-2)

      =7-46  

   t24    = -39