Đáp án:
Câu 2:
a) x + $\frac{1}{6}$ = $\frac{-3}{8}$
⇔ x = $\frac{-3}{8}$ - $\frac{1}{6}$
⇔ x = $\frac{-13}{24}$ .
Vậy x = $\frac{-13}{24}$ .
b) $\frac{1}{2}$x + $\frac{1}{8}$x = $\frac{3}{4}$
⇔ x.($\frac{1}{2}$ + $\frac{1}{8}$) = $\frac{3}{4}$
⇔ x.$\frac{5}{8}$ = $\frac{3}{4}$
⇔ x = $\frac{3}{4}$ : $\frac{5}{8}$
⇔ x = $\frac{3}{4}$ . $\frac{8}{5}$
⇔ x = $\frac{6}{5}$.
Vậy x = $\frac{6}{5}$.
c) 2 - |$\frac{3}{4}$ - x| = $\frac{7}{12}$
⇔ |$\frac{3}{4}$ - x| = 2 - $\frac{7}{12}$
⇔ |$\frac{3}{4}$ - x| = $\frac{17}{12}$
⇔ \(\left[ \begin{array}{l}\frac{3}{4} - x=\frac{17}{12}\\\frac{3}{4} - x=-\frac{17}{12}\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}x=\frac{3}{4} - \frac{17}{12}\\ x=\frac{3}{4} + \frac{17}{12}\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}x=\frac{-2}{3}\\ x=\frac{13}{6}\end{array} \right.\)
Vậy x ∈ {$\frac{-2}{3}$ ; $\frac{13}{6}$}.
d) (2x - 4,5) : $\frac{3}{4}$ - $\frac{1}{3}$ = 1
⇔ (2x - 4,5) : $\frac{3}{4}$ = 1 + $\frac{1}{3}$
⇔ (2x - 4,5) : $\frac{3}{4}$ = $\frac{4}{3}$
⇔ 2x - 4,5 = $\frac{4}{3}$ . $\frac{3}{4}$
⇔ 2x - 4,5 = 1
⇔ 2x = 1 + 4,5
⇔ 2x = $\frac{11}{2}$
⇔ x = $\frac{11}{2}$ : 2
⇔ x = $\frac{11}{2}$ . $\frac{1}{2}$
⇔ x = $\frac{11}{4}$.
Vậy x = $\frac{11}{4}$.
