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a ) 10 x X - 1 - 3 - 5 - 7 - ... - 19 = 2 + 4 + 6 + ... + 20
10 x X - 1 - 3 - 5 - 7 - ... - 19 = 110
10 x X - ( 1 + 3 + 5 + 7 + ... + 19 ) = 110
10 x X - 100 = 110
10 x X = 110 + 100
10 x X = 210
X = 210 : 10
X = 21
1) 5(x - 2) + 27 = 4x - 8
=> 5x - 10 + 27 = 4x - 8
=> 5x + 17 = 4x - 8
=> 5x - 4x = -8 - 17
=> x = -25
2) 3(x + 1) + 2(x + 2) = -13
=> 3x + 3 + 2x + 4 = -13
=> 5x + 7 = -13
=> 5x = -13 - 7
=> 5x = -20
=> x = -20 : 5
=> x = -4
3) (2x + 4)(5 - x) = 0
=> \(\orbr{\begin{cases}2x+4=0\\5-x=0\end{cases}}\)
=> \(\orbr{\begin{cases}2x=-4\\x=5\end{cases}}\)
=> \(\orbr{\begin{cases}x=-2\\x=5\end{cases}}\)
Vậy ...
4) x2 - 3x = 0
=> x(x - 3) = 0
=> \(\orbr{\begin{cases}x=0\\x-3=0\end{cases}}\)
=> \(\orbr{\begin{cases}x=0\\x=3\end{cases}}\)
Vậy ...
5) x2 - 3x + 2 = 0
=> x(x - 3) = -2
=> x(x - 3) = 1 . (1 - 3)
=> x = 1
a. \(\frac{-3}{2}-2x+\frac{3}{4}=-22\)2
=> \(-2x=-22+\frac{3}{2}-\frac{3}{4}\)
=> \(-2x=\frac{-85}{4}\)
=> \(x=\frac{-85}{4}:\left(-2\right)\)
=> \(x=\frac{85}{8}\)
b. \(\left(\frac{-2}{3}x-\frac{3}{5}\right).\left(\frac{3}{-2}-\frac{10}{3}\right)=\frac{2}{5}\)
=> \(\left(\frac{-2}{3}x-\frac{3}{5}\right).\frac{-29}{6}=\frac{2}{5}\)
=> \(\frac{-2}{3}x-\frac{3}{5}=\frac{2}{5}:\left(\frac{-29}{6}\right)\)
=> \(\frac{-2}{3}x-\frac{3}{5}=\frac{-12}{145}\)
=> \(\frac{-2}{3}x=\frac{-12}{145}+\frac{3}{5}\)
=> \(\frac{-2}{3}x=\frac{15}{29}\)
=> x = \(\frac{15}{29}:\frac{-2}{3}\)
=> x = \(\frac{-45}{58}\)
\(5\frac{9}{10}:\frac{3}{2}-\left[2\frac{1}{3}\times4\frac{1}{2}-2\times2\frac{1}{3}\right]:\frac{7}{4}\)
\(=\frac{59}{10}:\frac{3}{2}-\left[\frac{7}{3}\times\frac{9}{2}-2\times\frac{7}{3}\right]:\frac{7}{4}\)
\(=\frac{59}{10}\times\frac{2}{3}-\left[\left(\frac{9}{2}-2\right)\times\frac{7}{3}\right]:\frac{7}{4}\)
\(=\frac{59}{10}\times\frac{2}{3}-\left[\frac{5}{2}\times\frac{7}{3}\right]:\frac{7}{4}\)
\(=\frac{59}{10}\times\frac{2}{3}-\frac{35}{6}:\frac{7}{4}\)
\(=\frac{59}{15}-\frac{35}{6}\times\frac{4}{7}\)
\(=\frac{59}{15}-\frac{221}{42}\)
\(=-\frac{93}{70}\)
Học tốt !
\(\frac{3x}{2}-\frac{1}{3}=\frac{2}{5}-x\)
\(< =>\frac{9x-2}{6}=\frac{2-5x}{5}\)
\(< =>\left(9x-2\right)5=\left(2-5x\right)6\)
\(< =>45x-10=12-30\)
\(< =>45x+30x=12+10=22\)
\(< =>x=\frac{22}{75}\)
3x/2-1/3=2/5+x
3x/2-x=2/5+1/3
1/2x=11/15
x=11/15:1/2
x=22/15
đúng-**** cho mk nha!!!