b₃ = 12 b₆ = 324
b₃ = b₁ * q² b₆ = b₁ * q⁵
2Cos²x - 5Cosx + 3 = 0
Сделаем замену :
Cosx = m , - 1 ≤ m ≤ 1
2m² - 5m + 3 = 0
D = (- 5)² - 4 * 2 * 3 = 25 - 24 = 1
3^x + 3^x*3 = 4
3^x (1 + 3) = 4
3^x * 4 = 4
3^x = 1
3^x = 3^0
x = 0
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5^(2x) - 6*5^x + 5 = 0
5^x = t ==>
t^2 - 6t + 5 = 0
D = 36 - 20 = 16
t1 = (6 + 4)/2 = 10/2 = 5
t2 = (6 - 4)/2 = 2/2 = 1
5^x = 5
x = 1
5^x =1
x = 0