`|x-1|=4` `|5x-10|=15` Tìm `x` Biết ` `

2 bình luận về “`|x-1|=4` `|5x-10|=15` Tìm `x` Biết ` `”

1. |x-1|=4

   => \(\left[ \begin{array}{l}x-1=4\\x-1=-4\end{array} \right.\) 

   => \(\left[ \begin{array}{l}x=4+1\\x=4+(-1)\end{array} \right.\) 

   => \(\left[ \begin{array}{l}x=5\\x=3\end{array} \right.\) 

   Vậy x in {3;5}

   |5x-10|=15

   => \(\left[ \begin{array}{l}5x-10=-15\\5x-10=15\end{array} \right.\) 

   => \(\left[ \begin{array}{l}5x=15+10\\5x=-15+10\end{array} \right.\) 

   => \(\left[ \begin{array}{l}5x=25\\5x=-5\end{array} \right.\) 

   => \(\left[ \begin{array}{l}x=25:5\\x=-5:5\end{array} \right.\) 

   => \(\left[ \begin{array}{l}x=5\\x=-1\end{array} \right.\) 

   Vậy x in {5;-1}

   Trả lời
2. | x – 1 | = 4

   TH1:

   x – 1 = 4

   ⇒ x = 4 + 1

   ⇒ x = 5

   TH2:

   x – 1 = -4

   ⇒ x = -4 + 1

   ⇒ x = -3

   Vậy x ∈ { 5 ; -3 }

   _______

   | 5x – 10 | = 15

   TH1:

   5x – 10 = 15

   ⇒ 5x = 15 + 10

   ⇒ 5x = 25

   ⇒ x = 5

   TH2:

   5x – 10 = -15

   ⇒ 5x = -15 + 10

   ⇒ 5x = -5

   ⇒ x = -1

   Vậy x ∈ { 5 ; -1 }

    

   Trả lời