Question

find the value of n no. 20​

Answer 1

25^n-1 +100 =5^2n-1

(5^2)^n-1. +100 = 5^2n-1

5^2n-2 + 4×5^2 =5^2n-1

divide by 5^2

5^2n-4 + 4. =5^2n-3

it is only possible 1+ 4 =5

5^2n-4 =5^0 =1

2n -4 =0

2n =4

n =2