Toán Lớp 9: tìm m để $(m+1)x^{2}-2x+(m+1)=0$ có nghiệm
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Toán Lớp 9: tìm m để $(m+1)x^{2}-2x+(m+1)=0$ có nghiệm
Comments ( 1 )
+ Khi:m = – 1\\
\Leftrightarrow 0.{x^2} – 2x + 0 = 0\\
\Leftrightarrow x = 0\left( {tm} \right)\\
+ Khi:m \ne – 1\\
\Leftrightarrow \Delta ‘ \ge 0\\
\Leftrightarrow 1 – \left( {m + 1} \right).\left( {m + 1} \right) \ge 0\\
\Leftrightarrow {\left( {m + 1} \right)^2} \le 1\\
\Leftrightarrow – 1 \le m + 1 \le 1\\
\Leftrightarrow – 2 \le m \le 0\\
Vậy\, – 2 \le m \le 0
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