Question

the fiest and kast terms of an ap are 5 and 45 respectiveles it the sum of all its terms is 400 find the common difference and the number of terms​

Answer 1

ohk i answering this que

a = 5 , last term or an = 45 , sn = 400 ---- given

Step-by-step explanation:

find d = ? and n = ?

using this formula

sn = n/2 ( a + l )

400 = n/2 ( 5 +45 )

800 = n ( 50 )

800/50 = n

n = 16

then,

an = a + (n-1) d

45 = 5 + (16-1) d

40 = 15 d

d = 8/3

i hope you understand this que.