Question

Find n if the given value of x is the nth term of the given A.P.
(1) 25, 50, 75, 100,...; x = 1000​

Answer 1

a=25, d=25 and an=x=1000

an=a+(n-1)d

1000=25 + (n-1)25

1000-25=(n-1)25

975=(n-1)25

n-1=975/25

n-1=39

n=39+1

n=40

Answer 2

Answer:

$1000 = 25 + (n - 1)25 \\ 1000 = 25(1 + n - 1) \\ 1000 = 25n \\ n = 40$