Решение
1) 5^(2x + 1) - 3*5^(2x -1) = 550
5*5^(2x) - 0,6*5(^2x) = 550
(5^2x)*(5 - 3/5) = 550
(5^2x)*22 = 550*5
5^(2x) = 2750/ 22
5^(2x) = 125
5^(2x) = 5³
2x = 3
x = 1,5
2) 3^(x/2) * 5^(x/2) = 225
15^(x/2) = 15²
x/2 = 2
x = 4
3) 8*(2^2x) + 4*(2^x) - 4 = 0
2^x = t, t > 0
8*t² + 4t - 4 = 0
2t² + t - 1 = 0
D = 1 + 4*2*1 = 9
t₁ = (- 1 - 3)/4
t₁ = - 1 не удовлетворяет условию t > 0
t₂ = (- 1 + 3)/4
t₂ = 1/2
2^x = 1/2
2^x = 2⁻¹
x = - 1