Question

The first and last term of an A.P. are 5 and 45
respectively. If the sum of all its term is 400, find
difference .​

Answer 1

Sn=n/2(a+an)

400=n/2(50)

400/25=n

16=n

an=a +(n-1)d

45=5+15d

40/15=d

8/3=d

Answer 2

Answer:

N=16 D=8/3

Step-by-step explanation:

Sn=400

A1=5

An=45

Then

N=?

D=?

Now to fund Nth term we use

Sn=n/2×(a+l)

400=n/2 (5+45)

400×2=n (50)

800/50=n

16=n

Now using Sn formula we find D

Sn=n/2×(2a+(n-1)×d)

400=16/2×(2×5+(16-1)×d)

400/8=10+15d

50=5 (2+3d)

50/5=2+3d

10-2=3d

8/3=d

IF you find it use ful thank me and mark as brainliest for more help follow me