25^х=5 ^3 - х 3 sin ^2 2x+10sin 2x+3=0

25^x = 5^(3 - x)
5^(2x) = 5^(3 - x)
2x = 3 - x
2x + x = 3
3x = 3
x = 1

3sin²2x + 10sin2x + 3 = 0
3sin²2x + 9sin2x + sin2x + 3 = 0
3sin2x(3sin2x + 3) + (sin2x + 3) = 0
(3sin2x + 1)(3sin2x + 3) = 0
1) 3sin2x = -1
sin2x = -1/3
2x = (-1)ⁿ⁺¹arcsin(1/3) + πn, n ∈ Z
x =  1/2·(-1)ⁿ⁺¹arcsin(1/3) + πn/2, n ∈ Z
2) 3sin2x = -3
sin2x = -1
2x = -π/2 + 2πk, k ∈ Z
x = -π/4 + πk, k ∈ Z