Tìm x, biết: a) |x| = 1/4 + 4/7 b) |x-1| = 7/2 + -4/-3

* Hướng dẫn giải

a) $\left|x\right|=\frac{1}{4}+\frac{4}{7}\iff \left|x\right|=\frac{1.7+4.4}{28}=\frac{23}{28}$$\iff \left[\begin{array}{l}x=\frac{-23}{28}\\ x=\frac{23}{28}\end{array}\right.$

b) $\left|x-1\right|=\frac{7}{2}+\frac{-4}{-3}\iff \left|x-1\right|=\frac{29}{6}$$\iff \left[\begin{array}{l}x-1=\frac{29}{6}\\ x-1=\frac{-29}{6}\end{array}\right.\iff \left[\begin{array}{l}x=\frac{35}{6}\\ x=\frac{-23}{6}\end{array}\right.$