## Làm giúp mình nha , mìn cảm ơn nhiều lắm nha

Question

Làm giúp mình nha , mìn cảm ơn nhiều lắm nha

in progress 0
1 year 2020-10-21T23:45:00+00:00 1 Answers 67 views 0

7) $$\left\{ \begin{array}{l} y = 8\\ x = 12\\ z = 6 \end{array} \right.$$
$$\begin{array}{l} 2)\left\{ \begin{array}{l} x = \dfrac{9}{8}y\\ z = \dfrac{9}{{12}}y = \dfrac{3}{4}y\\ \dfrac{9}{8}y + y + \dfrac{3}{4}y = 69 \end{array} \right.\\ \to \left\{ \begin{array}{l} x = \dfrac{9}{8}y\\ z = \dfrac{3}{4}y\\ \left( {\dfrac{9}{8} + 1 + \dfrac{3}{4}} \right)y = 69 \end{array} \right.\\ \to \left\{ \begin{array}{l} x = \dfrac{9}{8}y\\ z = \dfrac{3}{4}y\\ \dfrac{{23}}{8}y = 69 \end{array} \right.\\ \to \left\{ \begin{array}{l} y = 24\\ x = 27\\ z = 18 \end{array} \right.\\ 4)\left\{ \begin{array}{l} x = \dfrac{3}{8}y\\ z = \dfrac{5}{8}y\\ 4.\dfrac{3}{8}y + 3y – 2.\dfrac{5}{8}y = 78 \end{array} \right.\\ \to \left\{ \begin{array}{l} x = \dfrac{3}{8}y\\ z = \dfrac{5}{8}y\\ \dfrac{{13}}{4}y = 78 \end{array} \right.\\ \to \left\{ \begin{array}{l} y = 24\\ x = 9\\ z = 15 \end{array} \right.\\ 6)\left\{ \begin{array}{l} x = \dfrac{4}{5}y\\ z = \dfrac{2}{5}y\\ \dfrac{4}{5}y + y – \dfrac{2}{5}y = 21 \end{array} \right.\\ \to \left\{ \begin{array}{l} \dfrac{7}{5}y = 21\\ x = \dfrac{4}{5}y\\ z = \dfrac{2}{5}y \end{array} \right.\\ \to \left\{ \begin{array}{l} y = 15\\ x = 12\\ z = 6 \end{array} \right.\\ 7)\left\{ \begin{array}{l} x = 4 + y\\ 4\left( {4 + y} \right) = 6y\\ z = \dfrac{6}{8}y \end{array} \right.\\ \to \left\{ \begin{array}{l} 2y = 16\\ x = 4 + y\\ z = \dfrac{6}{8}y \end{array} \right.\\ \to \left\{ \begin{array}{l} y = 8\\ x = 12\\ z = 6 \end{array} \right. \end{array}$$