Question

Tìm x biết :
a) | x - 3^2 | = x + 3
b) | 2 - x | + | -5x | = x

c) (| x + 1 ) . ( 5 - x )| = x + 1

Answer 1

a: =>|x-9|=x+3

\(\Leftrightarrow\left\{{}\begin{matrix}x>=-3\\\left(x-9-x-3\right)\left(x-9+x+3\right)=0\end{matrix}\right.\Leftrightarrow x=3\)

c: \(\Leftrightarrow\left\{{}\begin{matrix}\left(x+1\right)>=0\\\left(x+1\right)^2\cdot\left(x-5\right)^2=\left(x+1\right)^2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>=-1\\\left(x+1\right)^2\cdot\left(x-6\right)\left(x-4\right)=0\end{matrix}\right.\Leftrightarrow x\in\left\{-1;6;4\right\}\)