4y^2-81=(2y)²-9²=(2y-9)(2y+9)
8x³-125=(2x)³-5³=(2x-5)(4x²+10x+25)
Х3-6х2+36х+6х2-36х+219-2х2-18=х3-2х2+234
9ˣ - 2* 3⁽ˣ⁺²) + 45 = 0
3²ˣ - 2*3ˣ *3² + 45 = 0
3²ˣ - 18*3ˣ + 45 = 0
3ˣ = t
t² - 18t +45 = 0
по т.Виета t₁ = 15, t₂ = 3
1) t=15 2)t = 3
3ˣ = 15 3ˣ = 3
xlg3 = lg15 x = 1
x = lg15/lg3