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-4.|x-1| + (1/2-2,5)2 = -3
-4.|x-1| + (-2)2 = -3
-4.|x-1| + 4 = -3
-4.|x-1| = -3 - 4
-4.|x-1| = -7
|x-1| = (-7) : (-4)
|x-1| = 7/4
TH1: x - 1 = 7/4 => x = 7/4 + 1 = 11/4
TH2: 1 - x = 7/4 => x = 1 - 7/4 = -3/4
Vậy x = {11/4; -3/4}
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a: Ta có: \(\left(x-\dfrac{2}{5}\right)\left(x+\dfrac{2}{7}\right)>0\)
\(\Leftrightarrow\left[{}\begin{matrix}x>\dfrac{2}{5}\\x< -\dfrac{2}{7}\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\orbr{\begin{cases}x=\frac{1}{3}\\x=-\frac{1}{3}\end{cases}}\)
b)\(y=1\Rightarrow3x^2-2x=1\Leftrightarrow3x^2-2x-1=0..\left(a+b+c=0\Rightarrow\orbr{\begin{cases}x=1\\x=-\frac{1}{3}\end{cases}}\right)\)
Hoặc tiếp
\(3x^2-2x-1=0\Leftrightarrow x^2-2.\frac{1}{3}x+\frac{1}{9}-\frac{1}{9}-\frac{1}{3}=0\)
\(\Leftrightarrow\left(x-\frac{1}{3}\right)^2=\frac{4}{9}\hept{\begin{cases}x=1\\x=-\frac{1}{3}\end{cases}}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài làm:
1) \(\frac{3}{5}\div\frac{2x}{15}=\frac{1}{2}\div\frac{4}{5}\)
\(\Leftrightarrow\frac{9}{2x}=\frac{5}{8}\)
\(\Rightarrow10x=72\)
\(\Leftrightarrow x=\frac{36}{5}\)
2) \(-\frac{4}{2,5}\div\frac{3}{5}=\frac{1}{5}\div x\)
\(\Leftrightarrow\frac{1}{5}\div x=-\frac{8}{3}\)
\(\Rightarrow x=-\frac{3}{40}\)
3) \(0,12\div3=2x\div\frac{3}{5}\)
\(\Leftrightarrow\frac{1}{25}=\frac{10}{3}x\)
\(\Rightarrow x=\frac{3}{250}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(3-\frac{2}{3}+\frac{4}{3}\right):\left(2\frac{1}{3}-2,5\right)^2\)
\(=\left(\frac{7}{3}+\frac{4}{3}\right):\left(2\frac{1}{3}-2\frac{1}{2}\right)^2\)
\(=\frac{11}{3}:\left(-\frac{1}{6}\right)^2\)
\(=\frac{11}{3}:\frac{1}{36}\)
\(=\frac{11}{3}x\frac{36}{1}\)
\(=\frac{396}{3}\)
\(=132\)
(3-2/3+4/3):(2 1/3-2,5)2
= -17/6:121/36
=-36/121
1:55 phần 10