a) \(10,\left(3\right)+0,\left(4\right)-8,\left(6\right)\)

\(=\frac{31}{3}+\frac{4}{9}-\frac{26}{3}\)

\(=\left(\frac{31}{3}-\frac{26}{3}\right)+\frac{4}{9}=\frac{5}{3}+\frac{4}{9}=\frac{15}{9}+\frac{4}{9}=\frac{19}{9}\)

b) \(\left[12,\left(1\right)-2,3\left(6\right)\right]:4,\left(21\right)\)

\(=\left[\frac{109}{9}-\frac{71}{30}\right]:\frac{139}{33}\)

\(=-\frac{52}{45}:\frac{139}{33}=-\frac{52}{45}\cdot\frac{33}{139}=-\frac{572}{2085}\)(số xấu quá)

c) \(3\frac{1}{2}\cdot\frac{4}{49}-\left[2,\left(4\right)\cdot2\frac{5}{11}\right]:\frac{-42}{53}\)

\(=\frac{7}{2}\cdot\frac{4}{49}-\left[\frac{22}{9}\cdot\frac{27}{11}\right]\cdot\frac{-53}{42}\)

\(=\frac{2}{7}-6\cdot\left(-\frac{53}{42}\right)=\frac{2}{7}-\left(-\frac{53}{7}\right)=\frac{2}{7}+\frac{53}{7}=\frac{55}{7}\)

TH1 : 

\(\hept{\begin{cases}-x+2>0\\x-10< 0\end{cases}}\)    

\(\hept{\begin{cases}-x>-2\\x< 10\end{cases}}\)     

\(\hept{\begin{cases}x< 2\\x< 10\end{cases}\Rightarrow x< 2}\)       

TH2 : 

\(\hept{\begin{cases}-x+2< 0\\x-10>0\end{cases}}\)               

\(\hept{\begin{cases}-x< -2\\x>10\end{cases}}\)                              

\(\hept{\begin{cases}x>2\\x>10\end{cases}\Rightarrow x>10}\)                              

bạn ko được đăng câu hỏi linh tinh

ai hết hả

\(\frac{13}{42}-\left(\frac{55}{42}-78\right)\left(-\frac{1}{2}\right)^3\)

\(=\frac{13}{42}-\left(\frac{55}{42}-78\right)\left(-\frac{1}{8}\right)\)

\(=\frac{13}{42}+\frac{3221}{42}.\left(-\frac{1}{8}\right)\)

\(=\frac{13}{42}+-\frac{3221}{42}\)

\(=-\frac{1604}{21}\)

Ta có: \(\left(a+2b-3c-d\right)\left(a+2b+3c+d\right)\)

\(=\left[\left(a+2b\right)-\left(3c+d\right)\right]\cdot\left[\left(a+2b\right)+\left(3c+d\right)\right]\)

\(=\left(a+2b\right)^2-\left(3c+d\right)^2\)

\(=a^2+4ab+4b^2-9c^2-6cd-d^2\)

( a + 2b - 3c - d )( a + 2b + 3c + d )

= [ ( a + 2b ) - ( 3c + d ) ][ ( a + 2b ) + ( 3c + d ) ]

= ( a + 2b )² - ( 3c + d )²

= a² + 4ab + 4b² - ( 9c² + 6cd + d² )

= a² + 4ab + 4b² - 9c² - 6cd - d²

2¹⁷⁸ >  5⁷⁶

bạn phải trình bày rõ ra chứ!!!

172x² - 7⁹ : 98³ = 2^-3

<=> 172x² - 7⁹ : ( 2 . 7² )³ = 1/8

<=> 172x² - 7⁹ : ( 2³ . 7⁶ ) = 1/8

<=> 172x² - 7⁹ : 2³ : 7⁶ = 1/8

<=> 172x² - 7³ : 2³ = 1/8

<=> 172x² - ( 7 : 2 )³ = 1/8

<=> 172x² - 343/8 = 1/8

<=> 172x² = 43

<=> x² = 43/172 = 1/4

<=> x = ±1/2