0)} \atop {x\ne 3\qquad \qquad \qquad }} \right. \\\\\underline {x\in (-\infty ,-2)\cup (-2,3)\cup (3,+\infty )}\\\\2)\; \; f(x)=\frac{1}{x-3}\; \; \Rightarrow \; \; x-3\ne 0\; ,\; x\ne 3\\\\\underline {x\in (-\infty ,3)\cup (3,+\infty )}\\\\3)\; \; f(x)=x^2-1\; \; \Rightarrow \; \; \underline {x\in (-\infty ,+\infty )}" alt=" 1)\; \; f(x)=\frac{x}{(x^3+8)(x-3)^2}\; \; \Rightarrow \; \; (x^3+8)(x-3)^2\ne 0\\\\\left \{ {{x^3+8\ne 0} \atop {x-3\ne 0}} \right. \; \left \{ {{(x+2)(x^2-2x+4)\ne 0} \atop {x\ne 3}} \right. \; \left \{ {{x\ne -2\; \; (x^2-2x+4>0)} \atop {x\ne 3\qquad \qquad \qquad }} \right. \\\\\underline {x\in (-\infty ,-2)\cup (-2,3)\cup (3,+\infty )}\\\\2)\; \; f(x)=\frac{1}{x-3}\; \; \Rightarrow \; \; x-3\ne 0\; ,\; x\ne 3\\\\\underline {x\in (-\infty ,3)\cup (3,+\infty )}\\\\3)\; \; f(x)=x^2-1\; \; \Rightarrow \; \; \underline {x\in (-\infty ,+\infty )}" align="absmiddle" class="latex-formula">
![4)\; \; f(x)=|x|-2\; \; \Rightarrow \; \; \underline {x\in (-\infty ,+\infty )}\\\\5)\; \; f(x)=\frac{2x}{x^2-5x+4}\; \; \Rightarrow \; \; x^2-5x+4\ne 0\\\\x^2-5x+4=0\; \; \to \; \; x_1=1\; ,\; \; x_2=4\; \; (teorema\; Vieta)\\\\x\ne 1\; ,\; \underline {x\ne 4\\\\x\in (-\infty ,1)\cup (1,4)\cup (4,+\infty )} 4)\; \; f(x)=|x|-2\; \; \Rightarrow \; \; \underline {x\in (-\infty ,+\infty )}\\\\5)\; \; f(x)=\frac{2x}{x^2-5x+4}\; \; \Rightarrow \; \; x^2-5x+4\ne 0\\\\x^2-5x+4=0\; \; \to \; \; x_1=1\; ,\; \; x_2=4\; \; (teorema\; Vieta)\\\\x\ne 1\; ,\; \underline {x\ne 4\\\\x\in (-\infty ,1)\cup (1,4)\cup (4,+\infty )}](https://tex.z-dn.net/?f=+4%29%5C%3B+%5C%3B+f%28x%29%3D%7Cx%7C-2%5C%3B+%5C%3B+%5CRightarrow+%5C%3B+%5C%3B+%5Cunderline+%7Bx%5Cin+%28-%5Cinfty+%2C%2B%5Cinfty+%29%7D%5C%5C%5C%5C5%29%5C%3B+%5C%3B+f%28x%29%3D%5Cfrac%7B2x%7D%7Bx%5E2-5x%2B4%7D%5C%3B+%5C%3B+%5CRightarrow+%5C%3B+%5C%3B+x%5E2-5x%2B4%5Cne+0%5C%5C%5C%5Cx%5E2-5x%2B4%3D0%5C%3B+%5C%3B+%5Cto+%5C%3B+%5C%3B+x_1%3D1%5C%3B+%2C%5C%3B+%5C%3B+x_2%3D4%5C%3B+%5C%3B+%28teorema%5C%3B+Vieta%29%5C%5C%5C%5Cx%5Cne+1%5C%3B+%2C%5C%3B+%5Cunderline+%7Bx%5Cne+4%5C%5C%5C%5Cx%5Cin+%28-%5Cinfty+%2C1%29%5Ccup+%281%2C4%29%5Ccup+%284%2C%2B%5Cinfty+%29%7D)