Tìm x, biết: a) |x -2/3| = |-1/5| + 3/4 b) |x-3| = 1/5 | + |1/7 = 1/14|

* Hướng dẫn giải

a) $\left|x-\frac{2}{3}\right|=-\left|\frac{-1}{5}\right|+\frac{3}{4}\iff \left|x-\frac{2}{3}\right|=-\frac{1}{5}+\frac{3}{4}=\frac{11}{20}$$\iff \left[\begin{array}{l}x-\frac{2}{3}=\frac{11}{20}\\ x-\frac{2}{3}=\frac{-11}{20}\end{array}\right.\iff \left[\begin{array}{l}x=\frac{73}{60}\\ x=\frac{7}{60}\end{array}\right.$

b) $\left|x-3\right|=\frac{1}{5}+\left|\frac{1}{7}-\frac{1}{14}\right|\iff \left|x-3\right|=\frac{1}{5}+\frac{1}{14}=\frac{19}{70}$$\iff \left[\begin{array}{l}x-3=\frac{19}{70}\\ x-3=\frac{-19}{70}\end{array}\right.\iff \left[\begin{array}{l}x=\frac{229}{70}\\ x=\frac{191}{70}\end{array}\right.$