Bài 1 : Tìm x a. x -1 – ( 2015 ) = – ( | 2015| ) – |19| b. |x| – |3| = |-7| c. |x-1| – |7|=|15|- |-2|

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1. `#Xray`

   `a)x-1-(2015)=-(|2015|)-|19|`

   `⇒x-1-2015=-2015-19`

   `⇒x=1+2015-2015-19`

   `⇒x=-18`

   `b)|x|-|3|=|-7|`

   `⇒|x|-3=7`

   `⇒|x|=3+7=10`

   `⇒x=±10`

   `c)|x-1|-|7|=|15|-|-2|`

   `⇒|x-1|-7=15-2`

   `⇒|x-1|=15-2+7=20`

   `⇒x-1 =20 or x-1=-20`

   `1)x-1=20⇒x=21`

   `2)x-1=-20⇒x=-19`

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2. `x -1 – ( 2015 ) = – ( | 2015| ) – |19|`

   `⇔x= –  2015 – 19+1 + ( 2015 )`

   `⇔x=18 `

   `|x| – |3| = |-7|`

   `⇔|x|=|-7|+3`

   `⇔|x|=7+3`

   `⇔x=±10`

   ` |x-1| – |7|=|15|- |-2|`

   `⇔ |x-1| =15- 2+7`

   `⇔|x-1| =20`

   `th1 x-1=20`

   `⇒x=20+1=21`

   `th2 `

   `x-1=-20`

   `⇒x=-20+1=-19`

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