Question

[Mai Lạc]

1. |3x+2|+|9x²-4|=0
2. |x-5|+|x-25|=0
3. |2x-|-3,5|=|-6,5|
4. 5/3-|x-  1/3|=1/3

Answer 1

[Huy Hoàng]

1/\(\left|3x+2\right|+\left|9x^2-4\right|=0\)

<=> \(\hept{\begin{cases}\left|3x+2\right|=0\\\left|9x^2-4\right|=0\end{cases}}\)

<=> \(\hept{\begin{cases}3x+2=0\\9x^2-4=0\end{cases}}\)

<=> \(\hept{\begin{cases}x=-\frac{2}{3}\\x=\frac{2}{3}\end{cases}}\)

<=> \(x\in\varnothing\)

2/ \(\left|x-5\right|+\left|x-25\right|=0\)

<=> \(\hept{\begin{cases}\left|x-5\right|=0\\\left|x-25\right|=0\end{cases}}\)

<=> \(\hept{\begin{cases}x=5\\x=25\end{cases}}\)

<=> \(x\in\varnothing\)

3/ \(\left|2x\right|-\left|-3,5\right|=\left|-6,5\right|\)

<=> \(\left|2x\right|-3,5=6,5\)

<=> \(\left|2x\right|=10\)

<=> \(2x=\pm10\)

<=> \(x=\pm5\)

4/ \(\frac{5}{3}-\left|x-\frac{1}{3}\right|=\frac{1}{3}\)

<=> \(-\left|x-\frac{1}{3}\right|=-\frac{4}{3}\)

<=> \(\left|x-\frac{1}{3}\right|=\frac{4}{3}\)

<=> \(\orbr{\begin{cases}x-\frac{1}{3}=\frac{4}{3}\\x-\frac{1}{3}=-\frac{4}{3}\end{cases}}\)

<=> \(\orbr{\begin{cases}x=\frac{5}{3}\\x=-1\end{cases}}\)

Answer 2

[Hoàng Anh Tú]

l3x + 2l +l9x² - 4l = 0

=> l3x + 2l =0 hoặc l9x²-4l =0

=> 3x + 2 = 0           9x²-4  =0

=> 3x        = -2           9x²     =4

=> x          = -2:3       x²       = 4:9

=> x          = -2/3        x²       =4/9

=>                             x         =2/3  

Vậy x ={-2/3 ; 2/3}

câu 2 là tương tự