Question

in an ap if a=12 an=248 sn=7800 find n and d

Answer 1

Answer:

n=60

d= 4

Step-by-step explanation:

Sn= n/2(a+an)

7800=n/2(12+248)

7800 x 2/260=n

60=n

an= a+ (n-1)d

248= 12 + 59d

248-12=59d

236/59=d

4=d