Đáp án:
Min=0
Giải thích các bước giải:
\(\begin{array}{l}
\left\{ \begin{array}{l}
x + 2y = 3\\
- 4x - 2y = - 2m + 4
\end{array} \right.\\
\to \left\{ \begin{array}{l}
- 3x = 7 - 2m\\
y = \dfrac{{3 - x}}{2}
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = \dfrac{{2m - 7}}{3}\\
y = \dfrac{{3 - \dfrac{{2m - 7}}{3}}}{2} = \dfrac{{9 - 2m + 7}}{6}
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = \dfrac{{2m - 7}}{3}\\
y = \dfrac{{16 - 2m}}{6} = \dfrac{{8 - m}}{3}
\end{array} \right.\\
Có:x + y = \dfrac{{2m - 7}}{3} + \dfrac{{8 - m}}{3}\\
= \dfrac{{m + 1}}{3}
\end{array}\)
Để x+y min
⇔ (m+1) min
\(\begin{array}{l}
\Leftrightarrow m + 1 = 1\\
\Leftrightarrow m = 0\\
\to Min = 0
\end{array}\)
