3|4x-1|-2=19 Các anh chị giúp em với

2 bình luận về “3|4x-1|-2=19 Các anh chị giúp em với”

1. $3|4x-1|-2=19$

   ⇔$3|4x-1|=19+2$

   ⇔$3|4x-1|=21$

   ⇔$|4x-1|=21:3$

   ⇔$|4x-1|=7$

   ⇔\(\left[ \begin{array}{l}4x-1=7\\4x-1=-7\end{array} \right.\)

   ⇔\(\left[ \begin{array}{l}4x=7+1\\4x=-7+1\end{array} \right.\)

   ⇔\(\left[ \begin{array}{l}4x=8\\4x=-6\end{array} \right.\)

   ⇔\(\left[ \begin{array}{l}x=8:4\\x=-6:4\end{array} \right.\)

   ⇔\(\left[ \begin{array}{l}x=2\\x=-1,5\end{array} \right.\)

   Vậy \(\left[ \begin{array}{l}x=2\\x=-1,5\end{array} \right.\)

   Trả lời
2. 3 | 4x – 1 | – 2 = 19

   => 3 | 4x – 1 | = 19 + 2

   => 3 | 4x – 1 | = 21

   => | 4x – 1 | = 21 : 3

   => | 4x – 1 | = 7

   => $\left[\begin{matrix} 4x-1=7\\ 4x-1=-7\end{matrix}\right.$

   => $\left[\begin{matrix} 4x=7+1\\ 4x=-7+1\end{matrix}\right.$

   => $\left[\begin{matrix} 4x=8\\ 4x=-6\end{matrix}\right.$

   => $\left[\begin{matrix} x=8:4\\ x=-6:4\end{matrix}\right.$

   =>$\left[\begin{matrix} x=2\\ x=-\dfrac{3}{2}\end{matrix}\right.$

   Vậy x ∈ { 2 ; -3/2 }

   Trả lời