Question

Tìm x \(\in\) Z biết :

5 \(\le\) \(\left|2x-1\right|\) = 8

Answer 1

Ta có : \(\left|2x-1\right|=8\)

\(\Rightarrow\left[{}\begin{matrix}2x-1=8\\2x-1=-8\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}2x=9\\2x=-7\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=4,5\\x=-3,5\end{matrix}\right.\)

Thay \(x=4,5\Rightarrow\left|2x-1\right|=\left|2\times4,5-1\right|=8\) (nhận)

Thay \(x=-3,5\Rightarrow\left|2x-1\right|=\left|2\times\left(-3,5\right)-1\right|=8\)(nhận)

Vậy \(\left[{}\begin{matrix}x=4,5\\x=-3,5\end{matrix}\right.\)

~ Học tốt nha Nguyễn Ngọc Gia Hân ~