a) Nhân chéo phân số:
=> -2x = 0,3.7
<=> -2x = 2,1
<=> x = $\frac{2,1}{-2}$ = - $\frac{21}{20}$
b) $\frac{1}{3}$ + |x - $\frac{1}{6}$ | = 2$\frac{1}{3}$
<=> |x - $\frac{1}{6}$ | = $\frac{7}{3}$ - $\frac{1}{3}$
<=> |x - $\frac{1}{6}$ | = 2
<=> \(\left[ \begin{array}{l}x - \frac{1}{6}=2\\x - \frac{1}{6}=-2\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=\frac{13}{6}\\x=-\frac{11}{6}\end{array} \right.\)
c) |x-0,5| + |$\frac{2}{5}$ - 2x| = 0
Ta thấy |x-0,5| ≥ 0 ; |$\frac{2}{5}$ - 2x| ≥ 0
=> $\left \{ {{x-0,5=0} \atop {\frac{2}{5}- 2x = 0}} \right.$
<=> $\left \{ {{x=0,5} \atop {x=\frac{1}{5}}} \right.$ ( vô lý)
Vậy ko có giá trị nào thỏa mãn
