Tìm x, biết: A x + 11/12 = 23/24 b 11/8 - 3/8 cdot x = 1/8 — Không quảng cáo

Phương pháp giải

Dựa vào quy tắc tính với phân số.

a) $x + \frac{{11}}{{12}} = \frac{{23}}{{24}}$

$\begin{array}{l}x = \frac{{23}}{{24}} - \frac{{11}}{{12}}\\x = \frac{{23}}{{24}} - \frac{{22}}{{24}}\\x = \frac{1}{{24}}\end{array}$

Vậy $x = \frac{1}{{24}}$

b) $\frac{{11}}{8} - \frac{3}{8} \cdot x = \frac{1}{8}$

$\begin{array}{l}\frac{{11}}{8} - \frac{3}{8} \cdot x = \frac{1}{8}\\\frac{3}{8}x = \frac{{11}}{8} - \frac{1}{8}\\\frac{3}{8}x = \frac{5}{4}\\x = \frac{5}{4}:\frac{3}{8}\\x = \frac{{10}}{3}\end{array}$

Vậy $x = \frac{{10}}{3}$

c) ${\left( {{\rm{x}} - \frac{1}{2}} \right)^{\rm{2}}}{\rm{ = }}\frac{{\rm{1}}}{4}$

$\begin{array}{l}\left[ \begin{array}{l}{\rm{x}} - \frac{1}{2}{\rm{ = }}\frac{{\rm{1}}}{2}\\{\rm{x}} - \frac{1}{2}{\rm{ = }}\frac{{ - 1}}{2}\end{array} \right.\\\left[ \begin{array}{l}x = \frac{{\rm{1}}}{2} + \frac{1}{2}\\x = \frac{{ - 1}}{2} + \frac{1}{2}\end{array} \right.\\\left[ \begin{array}{l}x = 1\\x = 0\end{array} \right.\end{array}$

Vậy $x = 1;x = 0$.