Cho hs y=-2x +1 có đồ thị là đt (d) Tìm giá trị của m để đt (d') y=(2-m)x (vs m khác 2) cắt đt (d )tại điểm có hoành độ âm?

By Trang Ánh Nam -

Cho hs y=-2x +1 có đồ thị là đt (d) Tìm giá trị của m để đt (d') y=(2-m)x (vs m khác 2) cắt đt (d )tại điểm có hoành độ âm?

Giải: ta có phương trình hoành độ giao điểm:
-2x+1=(2-m)x
<=>(4-m)x=1
Để phương trình có nghiệm thì M khác 4
Khi đó phương trình có nghiệm:


Đề bài yêu cầu nghiệm âm nên x<0 =>4-m<0 => 4<m
Vậy đáp án: 4<m (vì 4<m thì m≠4 và m≠2)

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