c, |x| ≥ 0 (với mọi x)
=> |x| =-1 (vô lý)
=> vô nghiệm
f, |x-1|=4
<=> \(\left[ \begin{array}{l}x-1=4\\x-1=-4\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=5\\x=-3\end{array} \right.\)
Vậy x ∈ { 5;-3}
j, |x+4|= 5- (-1)
<=> |x+4| =6
<=> \(\left[ \begin{array}{l}x+4=6\\x+4=-6\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=2\\x=-10\end{array} \right.\)
Vậy x∈ {2; -10}
m, |x+2| -12=-1
<=> |x+2|= 11
<=> \(\left[ \begin{array}{l}x+2=11\\x+2=-11\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=9\\x=-13\end{array} \right.\)
Vậy x ∈{9; -13}
p, |x-3|= 7- (-2)
<=> |x-3|= 9
<=> \(\left[ \begin{array}{l}x-3=9\\x-3=-9\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=12\\x=-6\end{array} \right.\)
vậy x∈{12; -6}
