`a)|2x-15|=13`
`**2x-15=13`
`<=>2x=28`
`<=>x=14.`
`**2x-15=-13`
`<=>2x=-2`
`<=>x=-1.`
`b)|7x+3|=66`
`**7x+3=66`
`<=>7x=63`
`<=>x9`
`**7x+3=-66`
`<=>7x=-69`
`<=>x=-69/7`
`c)|5x-2|=0`
`<=>5x-2=0`
`<=>5x=2`
`<=>x=2/5`
\(a,\Leftrightarrow\left[{}\begin{matrix}2x-5=13\\2x-5=-13\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=9\\x=-4\end{matrix}\right.\)
Vậy ...
\(b,\Leftrightarrow\left[{}\begin{matrix}7x+3=66\\7x+3=-66\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=9\\x=-\dfrac{69}{7}\end{matrix}\right.\)
Vậy ...
\(c,\Leftrightarrow5x-2=0\)
\(\Leftrightarrow x=\dfrac{5}{2}\)
Vậy ...
a \(\Rightarrow\left[{}\begin{matrix}2x-5=13\\2x-5=-13\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}2x=18\\2x=-8\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=9\\x=-4\end{matrix}\right.\)
b \(\Rightarrow\left[{}\begin{matrix}7x+3=66\\7x+3=-66\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}7x=63\\7x=-69\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=9\\x=-\dfrac{69}{7}\end{matrix}\right.\)
c \(\Rightarrow5x-2=0\Rightarrow x=\dfrac{2}{5}\)
a)⇒\(\left[{}\begin{matrix}2x-5=13\\2x-5=-13\end{matrix}\right.\)=>\(\left[{}\begin{matrix}2x=13+5\\2x=-13+5\end{matrix}\right.\)=>\(\left[{}\begin{matrix}2x=18\\2x=8\end{matrix}\right.\)=>\(\left[{}\begin{matrix}x=9\\x=4\end{matrix}\right.\)
* Tìm x thuộc Z ak ???
a)|2x − 5| = 13
TH1 : 2x − 5 = 13
⇔ 2x = 18
⇔ x = 9 (t/m)
TH2 : 2x − 5 = − 13
⇔ 2x = − 8
⇔x = − 4
b)|7x + 3| = 66
TH1 : 7x + 3 = 66
⇔7x = 63
⇔x = 9 (t/m)
∗7x + 3 = − 66
⇔7x = − 69
⇔x = \(-\dfrac{69}{7}\) (ktm)
c)|5x − 2| = 0
⇔5x − 2 = 0
⇔5x = 2
⇔x = \(\dfrac{2}{5}\) (ktm)
Bài 4:
a) \(\left|2x-5\right|=13\)
\(\Rightarrow\left[{}\begin{matrix}2x-5=13\\2x-5=-13\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=9\\x=-4\end{matrix}\right.\)
b) \(\left|7x+3\right|=66\)
\(\Rightarrow\left[{}\begin{matrix}7x+3=66\\7x+3=-66\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=9\\x=\dfrac{-69}{7}\end{matrix}\right.\)
c) \(\left|5x-2\right|=0\)
\(\Rightarrow5x-2=0\)
\(\Rightarrow5x=0+2\)
\(\Rightarrow5x=2\)
\(\Rightarrow x=2:5\)
\(\Rightarrow x=\dfrac{2}{5}\)