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

* Hướng dẫn giải

$a)x:\frac{4}{5}+\frac{5}{2}=-3\frac{3}{4}\Rightarrow x:\frac{4}{5}=-3\frac{3}{4}-\frac{5}{2}$$\Rightarrow x:\frac{4}{5}=-\frac{11}{2}\Rightarrow x=-\frac{22}{5}.$

$b)\left|x-\frac{3}{4}\right|=1\frac{5}{4}\Rightarrow \left[\begin{array}{l}x-\frac{3}{4}=\frac{9}{4}\Rightarrow x=3\\ x-\frac{3}{4}=-\frac{9}{4}\Rightarrow x=-\frac{3}{2}.\end{array}\right.$