Question

[hoang thi hong hoa]

tim x biet : 4-|x-1/5|=-1/2

Answer 1

[Phùng Minh Quân]

Ta có : 

\(4-\left|x-\frac{1}{5}\right|=-\frac{1}{2}\)

\(\Leftrightarrow\)\(\left|x-\frac{1}{5}\right|=4-\left(-\frac{1}{2}\right)\)

\(\Leftrightarrow\)\(\left|x-\frac{1}{5}\right|=\frac{9}{2}\)

\(\Leftrightarrow\)\(\orbr{\begin{cases}x-\frac{1}{5}=\frac{9}{2}\\x-\frac{1}{5}=-\frac{9}{2}\end{cases}}\)

\(\Leftrightarrow\)\(\orbr{\begin{cases}x=\frac{9}{2}+\frac{1}{5}\\x=-\frac{9}{2}+\frac{1}{5}\end{cases}}\)

\(\Leftrightarrow\)\(\orbr{\begin{cases}x=\frac{43}{10}\\x=-\frac{43}{10}\end{cases}}\)

 Vậy \(x=\frac{43}{10}\) hoặc \(x=-\frac{43}{10}\)

Answer 2

[Dương Lam Hàng]

Ta có: \(4-\left|x-\frac{1}{5}\right|=\frac{-1}{2}\)

\(\Rightarrow\left|x-\frac{1}{5}\right|=4-\frac{-1}{2}\)

\(\Rightarrow\left|x-\frac{1}{5}\right|=\frac{9}{2}\)

\(\Rightarrow x-\frac{1}{5}=\pm\frac{9}{2}\)

Nếu \(x-\frac{1}{5}=\frac{9}{2}\Rightarrow x=\frac{9}{2}+\frac{1}{5}=\frac{47}{10}\)

Nếu \(x-\frac{1}{5}=\frac{-9}{2}\Rightarrow x=\frac{-9}{2}+\frac{1}{5}=\frac{-43}{10}\)

Vậy \(x=\left\{\frac{47}{10};\frac{-43}{10}\right\}\)

Chúc bạn năm mới vui vẻ!