7) log₃²x + 4log₃x +4 = 0
(log₃x + 2)²= 0
log₃x + 2 = 0
log₃x = -2
x = 3⁻² = 1/9
8) log₅x -2log₅5/log₅x = 1 | * log₅x
log₅²x -2 = log₅x
log₅x = t
t² - t - 2 = 0
по т. Виета t₁ = 2 и t₂ = -1
a) t₁ = 2 б) t₂ = -1
log₅x = 2 log₅x = -1
x = 5² = 25 x = 5⁻¹ = 1|5
9) log₂x + 12log₂2/log₂x = -7 | * log₂x
log₂²x + 12 = -7log₂x
log₂x = t
t² + 7t + 12 = 0
По т. Виета t₁ = - 4 и t₂ = -3
а) t₁ = -4 б) t₂ = -3
log₂x = -4 log₂x = -3
x = 2⁻⁴ = 1/16 x = 2⁻³ = 1/8