the first term of an AP is5 the last term is 45 and the sum is 400 find the number of the term and the common difference
Math
sonai1212
Question
the first term of an AP is5 the last term is 45 and the sum is 400 find the number of the term and the common difference
2 Answer

1. User Answers neelrambhia03
a = 5
l = 45
s = 400
400 = n(a + l)/2
800 = n(50)
n = 16
l = a + (n1)d
45 = 5 + 15d
40 = 15d
d = 40/15 = 8/3

2. User Answers Ishwarya12
Answer:
Given: a=5, an=45, sn=400
An=a+(n1)d
45=5+(n1)d
(n1)d=40
D=40/n1..........1
Sn= n/2(2a+(n1)d)
400=n/2(10+(n1)(40/n1)) [from 1]
800=n(10+40)
800=50n
80/5=n
N=16
Subs n in 1
D=40/15
D=8/3
Hope it helps u.....^_^