Question

The first term of an AP is 5 and the last term is 45. Ir the rum of all the
terms is 400, the number of terms is​

Answer 1

Step-by-step explanation:

first term a = 5 last term l = 45 and sn= 40

since ,sn= n/2(a+1)

=400,n/2(5+45)

400=n/2(50)

400=n*25

n=16

since l=a+(n-1)d

=45=5+(16-1)d

45-5=(15)d

40=15d

=d=40/15

d=8/3