Verified answer

(a^m)^n = a^(mn)

7^2x - 5^x - 25*7^2x + 25*5^x ≤ 0

- 24*7^2x + 24*5^x ≤ 0  | : 24

7^2x ≥ 5^x

49^x ≥ 5^x |:5^x>0

(49/5)^x ≥ 1

оcнование > 1  знаки не меняем

(49/5)^x ≥ (49/5)^0

x ≥ 0