\(C=3,14\times r\times r\)

\(C=3,14\times d\)

\(300-1000=-700\)

1+1=2

\(3\times3=9\)

Bài 1 :

a) \(\mid 2 x - 5 \mid = 4\)

\(\Rightarrow \backslash\text{orbr} \left{\right. 2 x - 5 = 4 \\ 2 x - 5 = - 4 \Rightarrow \backslash\text{orbr} \left{\right. 2 x = 9 \\ 2 x = 1 \Rightarrow \backslash\text{orbr} \left{\right. x = \frac{9}{2} \\ x = \frac{1}{2}\)

b) \(\frac{1}{3} - \mid \frac{5}{4} - 2 x \mid = \frac{1}{4}\)

\(\Rightarrow \mid \frac{5}{4} - 2 x \mid = \frac{1}{12}\)

\(\Rightarrow \backslash\text{orbr} \left{\right. \frac{5}{4} - 2 x = \frac{1}{12} \\ \frac{5}{4} - 2 x = - \frac{1}{12}\)

\(\Rightarrow \backslash\text{orbr} \left{\right. 2 x = \frac{7}{6} \\ 2 x = \frac{4}{3} \Rightarrow \backslash\text{orbr} \left{\right. x = \frac{7}{12} \\ x = \frac{2}{3}\)

c) \(\mid \frac{- 2}{3} \mid + \mid x - \frac{1}{3} \mid = \mid - 1 \mid - \mid \frac{- 1}{3} \mid\)

\(\Rightarrow \frac{2}{3} + \mid x - \frac{1}{3} \mid = 1 - \frac{1}{3}\)

\(\Rightarrow \frac{2}{3} + \mid x - \frac{1}{3} \mid = \frac{2}{3}\)

\(\Rightarrow \mid x - \frac{1}{3} \mid = 0 \Rightarrow x - \frac{1}{3} = 0 \Rightarrow x = \frac{1}{3}\)

d) \(\mid - \frac{1}{2} \mid - \mid x + \frac{1}{4} \mid = \mid - \frac{3}{4} \mid\)

\(\Rightarrow \frac{1}{2} - \mid x + \frac{1}{4} \mid = \frac{3}{4}\)

\(\Rightarrow \mid x + \frac{1}{4} \mid = - \frac{1}{4}\)

Vì \(\mid x \mid \geq 0 \Rightarrow\)ko có gtri nào của x thỏa mãn đề bài

Bài 2 :

a) \(\mid x - 1 \mid = 3 x + 2\)

\(\Rightarrow \backslash\text{orbr} \left{\right. x - 1 = 3 x + 2 \\ x - 1 = - 3 x - 2 \Rightarrow \backslash\text{orbr} \left{\right. x - 3 x = 2 + 1 \\ x + 3 x = - 2 + 1\)

\(\Rightarrow \backslash\text{orbr} \left{\right. - 2 x = 3 \\ 4 x = - 1 \Rightarrow \backslash\text{orbr} \left{\right. x = \frac{- 3}{2} \\ x = \frac{- 1}{4}\)

b|) \(\mid 9 + x \mid = 2 x \Rightarrow \backslash\text{orbr} \left{\right. 9 + x = 2 x \\ 9 + x = - 2 x\)

\(\Rightarrow \backslash\text{orbr} \left{\right. x - 2 x = - 9 \\ x + 2 x = - 9 \Rightarrow \backslash\text{orbr} \left{\right. - x = - 9 \\ 3 x = - 9 \Rightarrow \backslash\text{orbr} \left{\right. x = 9 \\ x = - 3\)

c) \(\mid x + 6 \mid - 9 = 2 x \Rightarrow \mid x + 6 \mid = 2 x + 9\)

\(\Rightarrow \backslash\text{orbr} \left{\right. x + 6 = 2 x + 9 \\ x + 6 = - 2 x - 9 \Rightarrow \backslash\text{orbr} \left{\right. x - 2 x = 9 - 6 \\ x + 2 x = - 9 - 6\)

\(\Rightarrow \backslash\text{orbr} \left{\right. - x = 3 \\ 3 x = - 15 \Rightarrow \backslash\text{orbr} \left{\right. x = - 3 \\ x = - 5\)

\(20+16=36\)

:))

...................

\(12+32=\) \(44\)

\(1+1=2\)