Đáp án:
h. Phương trình vô nghiệm
Giải thích các bước giải:
\(\begin{array}{l}
a.x + \frac{5}{8} = \frac{7}{8}\\
\to x = \frac{{7 - 5}}{8}\\
\to x = \frac{1}{4}\\
b.\frac{{14}}{5}x - 32 = - 90.\frac{2}{3}\\
\to \frac{{14}}{5}x - 32 = - 60\\
\to \frac{{14}}{5}x = - 28\\
\to x = - 10\\
c.x = \frac{7}{9} - \frac{4}{9}\\
\to x = \frac{1}{3}\\
d.\frac{9}{2} - 2x = \frac{{11}}{{14}}.\frac{{11}}{7}\\
\to \frac{9}{2} - 2x = \frac{{121}}{{98}}\\
\to 2x = \frac{9}{2} - \frac{{121}}{{98}}\\
\to 2x = \frac{{160}}{{49}}\\
\to x = \frac{{80}}{{49}}\\
e.\left| {x - 3} \right| = 7\\
\to \left[ \begin{array}{l}
x - 3 = 7\\
x - 3 = - 7
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 10\\
x = - 4
\end{array} \right.\\
g.\left| {x + \frac{2}{7}} \right| = \frac{1}{6}\\
\to \left[ \begin{array}{l}
x + \frac{2}{7} = \frac{1}{6}\\
x + \frac{2}{7} = - \frac{1}{6}
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = - \frac{5}{{42}}\\
x = - \frac{{19}}{{42}}
\end{array} \right.\\
h.2\left| {2x - \frac{2}{3}} \right| = \frac{3}{4} - 2\\
\to 2\left| {2x - \frac{2}{3}} \right| = - \frac{5}{4}\\
\to \left| {2x - \frac{2}{3}} \right| = - \frac{5}{8}\\
Do:\left| {2x - \frac{2}{3}} \right| \ge 0\forall x \in R
\end{array}\)
⇒ Phương trình vô nghiệm
