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18 tháng 11 2018

Sửa đề : Tìm m để bpt \(4mx>x+1\)có nghiệm .......v..........v.............

Ta có : \(4mx>x+1\)

        \(\Leftrightarrow4mx-x>1\)

        \(\Leftrightarrow x\left(4m-1\right)>1\)

       \(\Leftrightarrow x>\frac{1}{4m-1}\)

Để x > 9 thì \(\frac{1}{4m-1}\ge9\)

           \(\Leftrightarrow1\ge9\left(4m-1\right)\)

          \(\Leftrightarrow1\ge36m-9\)

          \(\Leftrightarrow10\ge36m\)

           \(\Leftrightarrow m\le\frac{18}{5}\)

18 tháng 11 2018

a, Câu hỏi tương đương với đề bài vì nghiệm chính là x nên 2 câu tương đương nhau

b, -5 > x

Mà \(x>\frac{1}{4m-1}\)

\(\Rightarrow-5>\frac{1}{4m-1}\)

Giải ra tìm được m

4 tháng 9 2017

Nguyễn Thanh HằngAkai HarumaRibi Nkok NgokMysterious Person

Ace LegonaNguyễn Thị Hồng NhungNguyễn Đình Dũng Toshiro Kiyoshi

Hung nguyenRồng Đỏ Bảo Lửa

14 tháng 10 2018

Bo may la binh day k di hieu ashdbfgbgygygggydfsghuyfhdguuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu3