Toán Lớp 9: Tìm m để ba đường thẳng sau đồng quy :
(d1) : y = x – 3 ; (d2) : y = -x + 6 ; (d3) : y = (1 – 2m)x + 3m – 5
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 9: Tìm m để ba đường thẳng sau đồng quy :
(d1) : y = x – 3 ; (d2) : y = -x + 6 ; (d3) : y = (1 – 2m)x + 3m – 5
Comments ( 1 )
x – 3 = – x + 6\\
\to 2x = 9\\
\to x = \dfrac{9}{2} \to y = \dfrac{3}{2}
\end{array}\)
Thay:x = \dfrac{9}{2};y = \dfrac{3}{2}\\
\to \left( {d3} \right):\dfrac{3}{2} = \left( {1 – 2m} \right).\dfrac{9}{2} + 3m – 5\\
\to 3 = 9\left( {1 – 2m} \right) + 6m – 10\\
\to 13 = 9 – 18m + 6m\\
\to – 12m = 4\\
\to m = – \dfrac{1}{3}
\end{array}\)