![image](https://tex.z-dn.net/?f=2%29%5C%3B%28x%5E2-4%29%5Clog_3%281-x%5E2-3x%29%3D0%5C%5CO.D.3.%3A%5C%5C1-x%5E2-3x%3E0%5CRightarrow+x%5Cin%5Cleft%28-%5Cfrac%7B3%2B%5Csqrt%7B13%7D%7D2%3B%5C%3B-%5Cfrac%7B3-%5Csqrt%7B13%7D%7D%7B2%7D%5Cright%29%5Capprox%28-3%2C3%3B%5C%3B0%2C3%29%5C%5C%5C%5C%5Cbegin%7Bcases%7Dx%5E2-4%3D0%5C%5C%5Clog_3%281-x%5E2-3x%29%3D0%5Cend%7Bcases%7D%5CRightarrow%5Cbegin%7Bcases%7Dx_1%3D-2%5C%5Cx_2%3D2%5C%5C1-x%5E2-3x%3D1%5Cend%7Bcases%7D%5CRightarrow%5C%5C%5CRightarrow%5Cbegin%7Bcases%7Dx_1%3D-2%5C%5Cx_2%3D2%5C%3BHe%5C%3Bnogx.%5C%5Cx%28x%2B3%29%3D0%5Cend%7Bcases%7D%5CRightarrow%5Cbegin%7Bcases%7Dx_1%3D-2%5C%5Cx_2%3D2%5C%5Cx_3%3D0%5C%5Cx_4%3D-3%5Cend%7Bcases%7D)
0\Rightarrow x\in\left(-\frac{3+\sqrt{13}}2;\;-\frac{3-\sqrt{13}}{2}\right)\approx(-3,3;\;0,3)\\\\\begin{cases}x^2-4=0\\\log_3(1-x^2-3x)=0\end{cases}\Rightarrow\begin{cases}x_1=-2\\x_2=2\\1-x^2-3x=1\end{cases}\Rightarrow\\\Rightarrow\begin{cases}x_1=-2\\x_2=2\;He\;nogx.\\x(x+3)=0\end{cases}\Rightarrow\begin{cases}x_1=-2\\x_2=2\\x_3=0\\x_4=-3\end{cases}" alt="2)\;(x^2-4)\log_3(1-x^2-3x)=0\\O.D.3.:\\1-x^2-3x>0\Rightarrow x\in\left(-\frac{3+\sqrt{13}}2;\;-\frac{3-\sqrt{13}}{2}\right)\approx(-3,3;\;0,3)\\\\\begin{cases}x^2-4=0\\\log_3(1-x^2-3x)=0\end{cases}\Rightarrow\begin{cases}x_1=-2\\x_2=2\\1-x^2-3x=1\end{cases}\Rightarrow\\\Rightarrow\begin{cases}x_1=-2\\x_2=2\;He\;nogx.\\x(x+3)=0\end{cases}\Rightarrow\begin{cases}x_1=-2\\x_2=2\\x_3=0\\x_4=-3\end{cases}" align="absmiddle" class="latex-formula">
![image](https://tex.z-dn.net/?f=3%29%5C%3B%5Cfrac%7B%5Clg+x%7D%7B1-%5Clg+x%7D%3D3%5C%5CO.D.3.%3A%5C%5C%5Cbegin%7Bcases%7Dx%3E0%5C%5C1-%5Clg+x%5Cneq0%5Cend%7Bcases%7D%5CRightarrow%5Cbegin%7Bcases%7Dx%3E0%5C%5Cx%5Cneq10%5Cend%7Bcases%7D%5CRightarrow+x%5Cin%280%3B%5C%0A%3B10%29%5Ccup%2810%3B%5C%3B%2B%5Cinfty%29%5C%5C%5C%5C%5Clg+x%3D3-3%5Clg+x%5C%5C4%5Clg+x%3D3%5C%5C%5Clg+x%3D%5Cfrac34%5C%5Cx%3D10%5E%7B%5Cfrac34%7D%3D%5Csqrt%5B4%5D%7B1000%7D)
0\\1-\lg x\neq0\end{cases}\Rightarrow\begin{cases}x>0\\x\neq10\end{cases}\Rightarrow x\in(0;\
;10)\cup(10;\;+\infty)\\\\\lg x=3-3\lg x\\4\lg x=3\\\lg x=\frac34\\x=10^{\frac34}=\sqrt[4]{1000}" alt="3)\;\frac{\lg x}{1-\lg x}=3\\O.D.3.:\\\begin{cases}x>0\\1-\lg x\neq0\end{cases}\Rightarrow\begin{cases}x>0\\x\neq10\end{cases}\Rightarrow x\in(0;\
;10)\cup(10;\;+\infty)\\\\\lg x=3-3\lg x\\4\lg x=3\\\lg x=\frac34\\x=10^{\frac34}=\sqrt[4]{1000}" align="absmiddle" class="latex-formula">