[tex]|x| - |x-2| > \dfrac{1}{3}[/tex]
[tex]x= 0 ~~ ; ~~ x - 2 =0 \\\\x = 0 ~~ ; ~~ x = 2[/tex]
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— + + x
— — + x -2
[tex]\text{I} )~~ \left \{ \begin{array}{l} x < 0 \\\\ -x -(-(x-2)) > \dfrac{1}{3} \end{array} \Leftrightarrow \left \{ \begin{array}{l} x < 0 \\\\- 2 > \dfrac{1}{3} ~~\varnothing \end{array} ~~\Leftrightarrow ~~ \varnothing[/tex]
[tex]\text{II} )~~ \left \{ \begin{array}{l} 0\leqslant x < 2 \\\\ x -(-(x-2)) > \dfrac{1}{3} \end{array} \Leftrightarrow \left \{ \begin{array}{l} 0\leqslant x < 2 \\\\ 2x-2 > \dfrac{1}{3} \end{array} \Leftrightarrow \left \{ \begin{array}{l} 0\leqslant x < 2 ~\\\\ x > \dfrac{7}{6} \end{array} \Leftrightarrow \dfrac{7}{6} < x < 2[/tex]
[tex]\text{III} )~~ \left \{ \begin{array}{l} x \geqslant 2 \\\\ x -(x-2) > \dfrac{1}{3} \end{array} \Leftrightarrow \left \{ \begin{array}{l} x \geqslant 2 \\\\2 > \dfrac{1}{3} \end{array} ~~\Leftrightarrow ~~ x \geqslant 2[/tex]
Находим объединение
[tex]\text{II}) ~x \in \bigg(\dfrac{7}{6} ~; ~2\bigg ) \\\\\\\ \text{III})~x \in [~~2 ~ ; ~ \infty ~)[/tex]
Выйдет
Ответ : [tex]x \in \bigg(\dfrac{7}{6} ~; ~\infty \bigg )[/tex] ( т.к это модульное неравенство )
[tex]|2x-1| -|x-4| > 4[/tex]
[tex]2x -1 =0 ~~ ; ~~ x -4 = 0 \\\\ x = 0,5 ~~~~~~ ; ~~ x = 4[/tex]
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— + + 2x - 1
— — + x - 4
[tex]\text{I} )~~ \left \{ \begin{array}{l} x < 0,5 \\\\ -(2x-1) -(-(x-4)) > 4 \end{array} \Leftrightarrow \left \{ \begin{array}{l} x < 0,5 \\\\- 2x + 1 + x -4 > 4 \end{array} \Leftrightarrow[/tex]
[tex]\Leftrightarrow \left \{ \begin{array}{l} x < 0,5 \\\\ x < -7 \end{array} \Leftrightarrow x < -7[/tex]
[tex]\text{II} )~~ \left \{ \begin{array}{l} 0,5\leqslant x < 4 \\\\ (2x-1) -(-(x-4)) > 4 \end{array} \Leftrightarrow \left \{ \begin{array}{l} 0,5\leqslant x < 4 \\\\ 2x - 1 + x -4 > 4 \end{array} \Leftrightarrow[/tex]
[tex]\Leftrightarrow \left \{ \begin{array}{l} 0,5\leqslant x < 4 \\\\ x > 3\end{array} \Leftrightarrow~~ 3 < x < 4[/tex]
[tex]\text{III} )~~ \left \{ \begin{array}{l} x \geqslant 4 \\\\ 2x+1 -(x-4) > 4 \end{array} \Leftrightarrow \left \{ \begin{array}{l} x \geqslant 4 \\\\ x+3 > 4 \end{array} ~~\Leftrightarrow ~~ x \geqslant 4[/tex]
[tex]\text{I}) ~x \in (-\infty ~ ; ~- 7 ~) \\\\\ \text{II})~x \in (~~3 ~ ; ~ 4 ~) \\\\ \text{III}) ~ x\in [ 4 ~ ; ~ \infty )[/tex]
После объединения :
Ответ : [tex]x \in (- \infty ~ ; ~ -7) \cup (3 ~; ~ \infty ~)[/tex]
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Answers & Comments
№1
[tex]|x| - |x-2| > \dfrac{1}{3}[/tex]
[tex]x= 0 ~~ ; ~~ x - 2 =0 \\\\x = 0 ~~ ; ~~ x = 2[/tex]
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— + + x
— — + x -2
[tex]\text{I} )~~ \left \{ \begin{array}{l} x < 0 \\\\ -x -(-(x-2)) > \dfrac{1}{3} \end{array} \Leftrightarrow \left \{ \begin{array}{l} x < 0 \\\\- 2 > \dfrac{1}{3} ~~\varnothing \end{array} ~~\Leftrightarrow ~~ \varnothing[/tex]
[tex]\text{II} )~~ \left \{ \begin{array}{l} 0\leqslant x < 2 \\\\ x -(-(x-2)) > \dfrac{1}{3} \end{array} \Leftrightarrow \left \{ \begin{array}{l} 0\leqslant x < 2 \\\\ 2x-2 > \dfrac{1}{3} \end{array} \Leftrightarrow \left \{ \begin{array}{l} 0\leqslant x < 2 ~\\\\ x > \dfrac{7}{6} \end{array} \Leftrightarrow \dfrac{7}{6} < x < 2[/tex]
[tex]\text{III} )~~ \left \{ \begin{array}{l} x \geqslant 2 \\\\ x -(x-2) > \dfrac{1}{3} \end{array} \Leftrightarrow \left \{ \begin{array}{l} x \geqslant 2 \\\\2 > \dfrac{1}{3} \end{array} ~~\Leftrightarrow ~~ x \geqslant 2[/tex]
Находим объединение
[tex]\text{II}) ~x \in \bigg(\dfrac{7}{6} ~; ~2\bigg ) \\\\\\\ \text{III})~x \in [~~2 ~ ; ~ \infty ~)[/tex]
Выйдет
Ответ : [tex]x \in \bigg(\dfrac{7}{6} ~; ~\infty \bigg )[/tex] ( т.к это модульное неравенство )
№2
[tex]|2x-1| -|x-4| > 4[/tex]
[tex]2x -1 =0 ~~ ; ~~ x -4 = 0 \\\\ x = 0,5 ~~~~~~ ; ~~ x = 4[/tex]
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— + + 2x - 1
— — + x - 4
[tex]\text{I} )~~ \left \{ \begin{array}{l} x < 0,5 \\\\ -(2x-1) -(-(x-4)) > 4 \end{array} \Leftrightarrow \left \{ \begin{array}{l} x < 0,5 \\\\- 2x + 1 + x -4 > 4 \end{array} \Leftrightarrow[/tex]
[tex]\Leftrightarrow \left \{ \begin{array}{l} x < 0,5 \\\\ x < -7 \end{array} \Leftrightarrow x < -7[/tex]
[tex]\text{II} )~~ \left \{ \begin{array}{l} 0,5\leqslant x < 4 \\\\ (2x-1) -(-(x-4)) > 4 \end{array} \Leftrightarrow \left \{ \begin{array}{l} 0,5\leqslant x < 4 \\\\ 2x - 1 + x -4 > 4 \end{array} \Leftrightarrow[/tex]
[tex]\Leftrightarrow \left \{ \begin{array}{l} 0,5\leqslant x < 4 \\\\ x > 3\end{array} \Leftrightarrow~~ 3 < x < 4[/tex]
[tex]\text{III} )~~ \left \{ \begin{array}{l} x \geqslant 4 \\\\ 2x+1 -(x-4) > 4 \end{array} \Leftrightarrow \left \{ \begin{array}{l} x \geqslant 4 \\\\ x+3 > 4 \end{array} ~~\Leftrightarrow ~~ x \geqslant 4[/tex]
[tex]\text{I}) ~x \in (-\infty ~ ; ~- 7 ~) \\\\\ \text{II})~x \in (~~3 ~ ; ~ 4 ~) \\\\ \text{III}) ~ x\in [ 4 ~ ; ~ \infty )[/tex]
После объединения :
Ответ : [tex]x \in (- \infty ~ ; ~ -7) \cup (3 ~; ~ \infty ~)[/tex]