Question

tìm x biết \x -3\ =2x+4

Answer 1

\x-3\=2x+4

<=> x-3=2x+4 hoặc x-3=-(2x+4)

<=>x-2x=4+3 ; x-3=-2x-4

<=>-x=7 ; x+2x=-4+3

<=>x=-7;3x=-1

<=>x=-7;x=-1/3

vậy x=-7;x=-1/3

Answer 2

Điều kiện: 2x+4\(\ge\)0 \(\Rightarrow2x\ge-4\Rightarrow x\ge-2\)

Khi đó: |x-3|=2x-4

\(\Rightarrow\left[{}\begin{matrix}x-3=2x+4\\x-3=-2x-4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x-2x=4+3\\x+2x=-4+3\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}-x=7\\3x=-1\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=7\left(TM\right)\\x=\dfrac{-1}{3}\left(TM\right)\end{matrix}\right.\)

Vậy...

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