Tìm x , y : | x – 3/4 | + | 2/5 – y | =0 02/10/2021 Bởi Kylie Tìm x , y : | x – 3/4 | + | 2/5 – y | =0
$\begin{array}{l} \left| {\frac{{x – 3}}{4}} \right| + \left| {\frac{2}{5} – y} \right| = 0\,\,\,\,\left( * \right)\\ Vi\,\,\,\left\{ \begin{array}{l} \left| {\frac{{x – 3}}{4}} \right| \ge 0\\ \left| {\frac{2}{5} – y} \right| \ge 0 \end{array} \right. \Rightarrow \left( * \right) \Leftrightarrow \left\{ \begin{array}{l} \frac{{x – 3}}{4} = 0\\ \frac{2}{5} – y = 0 \end{array} \right.\\ \Leftrightarrow \left\{ \begin{array}{l} x – 3 = 0\\ y = \frac{2}{5} \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l} x = 3\\ y = \frac{2}{5} \end{array} \right.. \end{array}$ Bình luận
Đáp án:
Giải thích các bước giải:
$\begin{array}{l}
\left| {\frac{{x – 3}}{4}} \right| + \left| {\frac{2}{5} – y} \right| = 0\,\,\,\,\left( * \right)\\
Vi\,\,\,\left\{ \begin{array}{l}
\left| {\frac{{x – 3}}{4}} \right| \ge 0\\
\left| {\frac{2}{5} – y} \right| \ge 0
\end{array} \right. \Rightarrow \left( * \right) \Leftrightarrow \left\{ \begin{array}{l}
\frac{{x – 3}}{4} = 0\\
\frac{2}{5} – y = 0
\end{array} \right.\\
\Leftrightarrow \left\{ \begin{array}{l}
x – 3 = 0\\
y = \frac{2}{5}
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x = 3\\
y = \frac{2}{5}
\end{array} \right..
\end{array}$