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3 câu trả lời 167
Hệ điều kiện tiếp xúc:
$\left\{\begin{array}{l} x^3 +3mx-2=0 \\ (x^3 +3mx-2)'=0'\end{array} \right.\\ \Leftrightarrow \left\{\begin{array}{l} x^3 +3mx-2=0 \\ 3x^2 +3m=0\end{array} \right.\\ \Leftrightarrow \left\{\begin{array}{l} 3x^3 +3mx-2x^3-2=0 \\ 3x^2 +3m=0\end{array} \right.\\ \Leftrightarrow \left\{\begin{array}{l} 3x(x^2 +3m)-2x^3-2=0 \\ 3x^2 +3m=0\end{array} \right.\\ \Leftrightarrow \left\{\begin{array}{l} -2x^3-2=0 \\ 3x^2 +3m=0\end{array} \right.\\ \Leftrightarrow \left\{\begin{array}{l} x^3 =-1 \\ 3x^2 +3m=0\end{array} \right.\\ \Leftrightarrow \left\{\begin{array}{l} x=-1 \\ 3+3m=0\end{array} \right.\\ \Leftrightarrow \left\{\begin{array}{l} x=-1 \\ m=-1\end{array} \right.$
Đáp án:
$A.$
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