Đáp án:
$a. x = \frac{5}{8}$
$c. x = - \frac{20}{3}$
$e. x = \frac{460}{183}$
$m. x = \frac{19}{20}$
Giải thích các bước giải:
$a. \frac{-3}{2} - 2x + \frac{3}{4} = - 2$
⇔ $( \frac{-3}{2} + \frac{3}{4} ) - 2x = - 2$
⇔ $( \frac{-6}{4} + \frac{3}{4} ) - 2x = - 2$
⇔ $\frac{-3}{4} - 2x = - 2$
⇔ $2x = \frac{-3}{4} + 2$
⇔ $2x = \frac{-3+2×4}{4}$
⇔ $2x = \frac{-3+8}{4}$
⇔ $2x = \frac{5}{4}$
⇔ $x = \frac{5}{4} : 2$
⇔ $x = \frac{5}{8}$
$c. \frac{x}{2} - ( \frac{3x}{5} - \frac{13}{5} ) = - ( \frac{7}{5} + \frac{7}{10}x )$
⇔ $\frac{x}{2} - \frac{3x-13}{5} = - \frac{7}{5} - \frac{7}{10}x$
⇔ $\frac{5x}{10} - \frac{6x-26}{10} = - \frac{14}{10} - \frac{7}{10}x$
⇔ $\frac{5x-6x+26}{10} = \frac{-14-7x}{10}$
⇔ $- x + 26 = - 14 - 7x$
⇔ $- x + 7x = - 14 - 26$
⇔ $6x = - 40$
⇔ $x = - \frac{40}{6}$
⇔ $x = - \frac{20}{3}$
$e. \frac{2}{3x} - \frac{3}{12} = \frac{4}{5} - ( \frac{7}{x} - 2 )$ $( x \ne 0 )$
⇔ $\frac{2}{3x} - \frac{1}{4} = \frac{4}{5} - \frac{7}{x} + 2$
⇔ $\frac{2}{3x} + \frac{7}{x} = \frac{4}{5} + 2 + \frac{1}{4}$
⇔ $\frac{2+7×3}{3x} = \frac{4×4+2×4×5+1×5}{4×5}$
⇔ $\frac{2+21}{3x} = \frac{16+40+5}{20}$
⇔ $\frac{23}{3x} = \frac{61}{20}$
⇔ $23×20 = 61×3x$
⇔ $183x = 460$
⇔ $x = \frac{460}{183}$
$m. ( \frac{3}{2} - \frac{2}{-5} ) : x - \frac{1}{2} = \frac{3}{2}$ $( x \ne 0 )$
⇔ $( \frac{3}{2} + \frac{2}{5} ) : x = \frac{3}{2} + \frac{1}{2}$
⇔ $\frac{3×5+2×2}{2×5} : x = 2$
⇔ $\frac{15+4}{10} = 2x$
⇔ $2x = \frac{19}{10}$
⇔ $x = \frac{19}{10} : 2$
⇔ $x = \frac{19}{20}$
