Question

Найдите область определения функции: (картинка с заданием закреплена)


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Answer 1

$1)\ \ f(x)=\dfrac{3x+1}{x^2-3x+2}\ \ \ \to \ \ f(x)=\dfrac{3x+1}{(x-1)(x-2)}\\\\\\OOF:\ \ x\ne 1\ ,\ x\ne 2\ \ \ \to \ \ \ x\in (-\infty ;1)\cup (1;2)\cup (2;+\infty )\\\\\\2)\ \ f(x)=\sqrt{x^2-1}+\dfrac{1}{3-x}\\\\\\OOF:\ \ \left\{\begin{array}{l}(x-1)(x+1)\geq 0\\3-x\ne 0\end{array}\right\ \ \left\{\begin{array}{l}x\in (-\infty ;-1\ ]\cup [\ 1;+\infty )\\x\ne 3\end{array}\right\\\\\\x\in (-\infty ;-1\ ]\cup [\ 1\, ;\, 3)\cup (\, 3\, ;+\infty )$

$3)\ \ f(x)=\dfrac{1}{\sqrt{3+|x|}}\\\\\\OOF:\ \ 3+|x|>0\ \ ,\ \ |x|>-3\ \ \ \Rightarrow \ \ x\in (-\infty ;+\infty )\\\\\\4)\ \ f(x)=\sqrt{(1-x)(1+5x)}\\\\OOF:\ \ (1-x)(1+5x)\geq 0\ \ \to \ \ \ \ (x-1)(5x+1)\leq 0\ ,\\\\znaki:\ \ \ +++[-\dfrac{1}{5}\, ]---[\, 1\, ]+++\\\\x\in \Big[-\dfrac{1}{5}\, ;\, 1\ \Big]$

$5)\ \ f(x)=\dfrac{x}{|x|}\ \ ,\ \ OOF:\ \ x\ne 0\\\\x\in (-\infty ;0\ )\cup (\ 0;+\infty )\\\\\\6)\ \ f(x)=\sqrt{x-2}+\sqrt{4-x}\\\\\\OOF:\ \ \left\{\begin{array}{l}x-2\geq 0\\4-x\geq 0\end{array}\right\ \ \left\{\begin{array}{l}x\geq 2\\x\leq 4\end{array}\right\ \ \ \Rightarrow \ \ 2\leq x\leq 4\\\\\\x\in [\ 2\, ;\, 4\ ]$