Question

tìm x biết :

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

2,\(x+\left|x\right|\)=2x

Answer 1

1.

\(\left|x-1\right|+2x=4\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x< 1\\1-x+2x=4;x=3\left(l\right)\end{matrix}\right.\\\left\{{}\begin{matrix}x\ge1\\x-1+2x=4;x=\dfrac{5}{3}\left(n\right)\end{matrix}\right.\end{matrix}\right.\)

nghiệm x =5/3

2.

\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x< 0\\x-x=2x;=>x=0\left(l\right)\end{matrix}\right.\\\left\{{}\begin{matrix}x\ge0\\x+x=2x;2x=2x\left(\forall x\right)\end{matrix}\right.\end{matrix}\right.\)

đúng mọi x>=0