Toán Lớp 10: Tìm m để PT x ² + 2( m – 1) x + (x + 1) = 0 có nghiệm kép bằng ?
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 10: Tìm m để PT x ² + 2( m – 1) x + (x + 1) = 0 có nghiệm kép bằng ?
Comments ( 1 )
{x^2} + 2\left( {m – 1} \right).x + x + 1 = 0\\
\Leftrightarrow {x^2} + \left( {2m – 1} \right).x + 1 = 0
\end{array}$
\Delta = 0\\
\Leftrightarrow {\left( {2m – 1} \right)^2} – 4.1 = 0\\
\Leftrightarrow {\left( {2m – 1} \right)^2} = 4\\
\Leftrightarrow \left[ \begin{array}{l}
2m – 1 = 2\\
2m – 1 = – 2
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l}
m = \dfrac{3}{2}\\
m = – \dfrac{1}{2}
\end{array} \right.\\
+ Khi:m = \dfrac{3}{2} \Leftrightarrow x = – 1\\
+ Khi:m = – \dfrac{1}{2} \Leftrightarrow x = 1
\end{array}$