5 ^2х+1 + 3*5 ^2х-1 >3500

Question

5 ^2х+1 + 3*5 ^2х-1 >3500

Answer 1

(5^2x-1)(5^2+3)>3500
(5^2x-1)*28>3500
5^2x-1>125
5^2x-1>5^3
2x-1>3,   2x>4,   x>2