Question

tìm x :

a, \(\left|3x+8\right|=2x+4\)

b, \(2\left|2x+1\right|-x=15\)

c, \(\left|3x+7\right|=3x+7\)

d, \(\left|2x-5\right|+2x=5\)

Answer 1

a: \(\Leftrightarrow\left\{{}\begin{matrix}x>=-2\\\left(3x+8+2x+4\right)\left(3x+8-2x-4\right)=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>=-2\\\left(5x+12\right)\left(x+4\right)=0\end{matrix}\right.\Leftrightarrow x\in\varnothing\)

b: \(\Leftrightarrow\left|4x+2\right|=x+15\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>=-15\\\left(4x+2+x+15\right)\left(4x+2-x-15\right)=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>=-15\\\left(5x+17\right)\left(3x-13\right)=0\end{matrix}\right.\Leftrightarrow x\in\left\{-\dfrac{17}{5};\dfrac{13}{3}\right\}\)

c: =>3x+7>=0

hay x>=-7/3

d: =>|2x-5|=-2x+5

=>2x-5<=0

hay x<=5/2