Question

tìm x: a, /3x/=1-3x b, /x-\(\dfrac{1}{5}\)/=\(\dfrac{1}{5}\)-x

Answer 1

a) \(\left|3x\right|=1-3x\)

TH₁: \(3x>0\Rightarrow x>0\)

Ta có: \(3x=1-3x\)

\(\Rightarrow3x+3x=1\)

\(\Rightarrow6x=1\Rightarrow x=\frac{1}{6}\) (t/m)

TH₂: \(3x< 0\Rightarrow x< 0\)

Lại có: \(3x=-1+3x\)

\(\Rightarrow3x-3x=-1\)

\(\Rightarrow0=-1\) (loại)

Vậy \(x=\frac{1}{6}.\)

b) \(\left|x-\frac{1}{5}\right|=\frac{1}{5}-x\)

\(\Rightarrow\left|x-\frac{1}{5}\right|=-\left(x-\frac{1}{5}\right)\)

\(\Rightarrow x-\frac{1}{5}\le0\)

\(\Rightarrow x\le0+\frac{1}{5}\)

\(\Rightarrow x\le\frac{1}{5}.\)

Vậy \(x\le\frac{1}{5}.\)