Question

[quynh nhu nguyen]

BT3. Tìm x, biết:

a/ |x|=\(\dfrac{1}{2}\) ; b/ |x|= 3,12; c/ |x|= 0; d/ |x|=2\(\dfrac{1}{7}\) ;

BT3. Tìm x, biết:

a/|x|=2,1; b/|x|\(\dfrac{17}{9}\) và x < 0; c/|x| = 1\(\dfrac{2}{5}\) ; d/ |x|= 0,35 và x > 0.

BT4. Tim x, biet:

a/ | x - 1,7| =2,3; b/ | x+\(\dfrac{3}{4}\) | - \(\dfrac{1}{3}\) = 0

Answer 1

[Nguyễn Thanh Hằng]

1, a/ \(\left|x\right|=\dfrac{1}{2}\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=\dfrac{-1}{2}\end{matrix}\right.\)

Vậy .............

b/ \(\left|x\right|=3,12\Leftrightarrow\left[{}\begin{matrix}x=3,12\\x=-3,12\end{matrix}\right.\)

Vậy ...........

c/ \(\left|x\right|=0\Leftrightarrow x=0\)

Vậy ..........

d/ \(\left|x\right|=2\dfrac{1}{7}\) \(\Leftrightarrow\left[{}\begin{matrix}x=2\dfrac{1}{7}\\x=-2\dfrac{1}{7}\end{matrix}\right.\)

Vậy ..............

2, a/ \(\left|x\right|=2,1\Leftrightarrow\left[{}\begin{matrix}x=2,1\\x=-2,1\end{matrix}\right.\)

Vậy ...........

b/ \(\left|x\right|=\dfrac{17}{9}\) ; \(x< 0\)

\(\Leftrightarrow x=-\dfrac{17}{9}\)

Vậy ..........

c/ \(\left|x\right|=1\dfrac{2}{5}\Leftrightarrow\left[{}\begin{matrix}x=1\dfrac{2}{5}\\x=-1\dfrac{2}{5}\end{matrix}\right.\)

Vậy ...........

d/ \(\left|x\right|=0,35\) ; \(x>0\Leftrightarrow x=0,35\)

3, a/ \(\left|x-1,7\right|=2,3\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1,7=2,3\\x-1,7=-2,3\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-0,6\end{matrix}\right.\)

Vậy ...........

b/ \(\left|x+\dfrac{3}{4}\right|-\dfrac{1}{3}=0\)

\(\Leftrightarrow\left|x+\dfrac{3}{4}\right|=\dfrac{1}{3}\)

\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{3}{4}=\dfrac{1}{3}\\x+\dfrac{3}{4}=-\dfrac{1}{3}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-5}{12}\\x=-\dfrac{13}{12}\end{matrix}\right.\)

Vậy ...........

Answer 2

[Đạt Trần]

Đề dễ lắm sao ko tự làm đi