Giải thích các bước giải:
$\begin{array}{l} 174,a)\,\left| {x{\rm{ }} + {\rm{ }}1} \right|{\rm{ }} = {\rm{ }}5\\ \Leftrightarrow x + 1 = 5(do\,x \ge 0\,nen\,x + 1 > 0)\\ \Leftrightarrow x = 4\\ b)\,\left| {x{\rm{ }} - {\rm{ }}3} \right|{\rm{ }} = {\rm{ }}7\\ \Leftrightarrow x - 3 = - 7(do\,x < 3\,nen\,x - 3\, < 0)\\ \Leftrightarrow x = - 4\\ c)\,x{\rm{ }} + {\rm{ }}\left| {2{\rm{ }} - {\rm{ }}x} \right|{\rm{ }} = {\rm{ }}6\\ \Leftrightarrow x + x - 2 = 6(do\,x > 2\,nen\,x - 2 > 0)\\ \Leftrightarrow 2x = 8\\ \Leftrightarrow x = 4\\ 175.\,a)\, - 3 \le x < 3\\ \Rightarrow x \in \left\{ { - 3; - 2; - 1;0;1;2} \right\}\\ b)\,khong\,\exists x\\ c)\,x < - 2,x \in Z\\ 176.\,a)\,\left| x \right|{\rm{ }} = {\rm{ }}7\\ \Leftrightarrow x = \pm 7\\ b)\,\left| x \right|{\rm{ }} < {\rm{ }}7\\ \Leftrightarrow - 7 < x < 7\\ \Leftrightarrow x \in \left\{ { - 6, - 5, - 4, - 3, - 2, - 1,0, - 1,2,3,4,5,6} \right\}\\ c)\,\left| x \right| > 7\\ \Leftrightarrow \left[ \begin{array}{l} x > 7\\ x < - 7 \end{array} \right. \end{array}$
