Log₂² x² - 15log₂x - 4≤0

[latex]4 log_{2} ^{2} x - 15 log_{2}x - 4 \leq 0 [/latex] [latex] log_{2} x = t[/latex] 4t² - 15t - 4 ≤ 0 D = 225 + 64 = 289 t = (15 + 17)/8 = 4    или    t = (15 - 17)/8 = - 1/4 см. рис. t ≥ - 1/4   это система t ≤ 4 [latex] \left \{ {{log_{2} x \geq - \frac{1}{4}} \atop {log_{2} x \leq 4}} \right. [/latex] x ≥ 2 ^ (-1/4) x ≤ 2^4 [latex] \left \{ {{x \geq \frac{1}{ \sqrt[4]{2} } } \atop {x \leq 64}} \right. [/latex]