Question

tìm x biết: |3-5x|\(\ge7\)

Answer 1

Ta có :

\(\left|3-5x\right|\ge7\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}3-5x\ge7\\5x-3\ge7\end{array}\right.\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}-5x\ge4\\5x\ge10\end{array}\right.\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}x\le-\frac{4}{5}\\x\ge2\end{array}\right.\)

Vậy ........

Answer 2

|3-5x|>=7

=>3-5x >=7 hoặc 3-5x>=-7

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