Khoảng giá trị của x khi y = 1 trong hệ bất phương trình \(\left\{ \begin{matrix} x+y\ge 1 \\ 2x-3y<5 \\ \end{matrix} \right.\) là?
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
Khi y = 1, hệ bất phương trình trở thành:
\(\left\{ \begin{matrix} x+y\ge 1 \\ 2x-3.1<5 \\ \end{matrix}\Leftrightarrow \left\{ \begin{matrix} x\ge 0 \\ 2x<8 \\ \end{matrix}\Leftrightarrow \right. \right.\left\{ \begin{matrix} x\ge 0 \\ x<4 \\ \end{matrix}\Leftrightarrow \right.0\le x<4\)
Vậy x ∈ [0; 4).
Đáp án đúng là: A
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