Question

In an A.P, if a=-2,d=5,Sn=568 then find n, l ​

Answer 1

Answer:  n = 16 and l = 73

Step-by-step explanation:Sn = n/2 (2a+(n-1)d)

568=n/2(2*-2+(n-1)5)

1136=  -4n+5n^2 -5n

5n^2 -9n -1136=0

5n^2 -80n+71n -1136=0

5n(n-16) +71(n-16) =0

(5n+71) is rejected as n cannot be negative

So, n=16

l = An = a+(n-1)d

       An= -2+(16-1)5

       An= -2+75

So, l=An= 73

Answer 2

Answer:

All the best guys for this answer