Question

tìm x biết

1)/x+2/ + /2x+1/= 4x​

2) /x+1/+/x+2/+ 4x +7

Answer 1

dấu / là trị tuyệt đối nha

Answer 2

1.)

\(\left|x+2\right|+\left|2x+1\right|=4x\)

TH1 : \(x< -2\)

\(\Rightarrow\left|x+2\right|+\left|2x+1\right|=\left(-x-2\right)-\left(2x+1\right)=4x\\ \Leftrightarrow-3x-3=4x\\ \Rightarrow7x=-3\\ \Rightarrow x=-\dfrac{-3}{7}\left(loai\right)\)

TH2 : \(-2\le x\le-\dfrac{1}{2}\)

\(\Rightarrow\left|x+2\right|+\left|2x+1\right|=\left(x+2\right)+\left(2x+1\right)=4x\\ \Leftrightarrow3x+3=4x\\ \Leftrightarrow x=3\left(loai\right)\)

TH3 : x>-1/2

\(\left|x+2\right|+\left|2x+1\right|=\left(x+2\right)+\left(2x+1\right)=4x\\ \Leftrightarrow x=3\left(TM\right)\)

Vậy x=3