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Ta có : \(\left|2x-1\right|-\frac{1}{2}=\frac{1}{3}\)
=> \(\left|2x-1\right|=\frac{5}{6}\)
TH1 : \(2x-1\ge0\left(x\ge\frac{1}{2}\right)\)
=> \(\left|2x-1\right|=2x-1=\frac{5}{6}\)
=> \(x=\frac{\frac{5}{6}+1}{2}=\frac{11}{12}\)( TM )
TH2 : \(2x-1< 0\left(x< \frac{1}{2}\right)\)
=> \(\left|2x-1\right|=1-2x=\frac{5}{6}\)
=> \(x=\frac{\frac{5}{6}-1}{-2}=\frac{1}{12}\) ( TM )
Vậy phương trình trên có tập nghiệm là \(S=\left\{\frac{1}{12};\frac{11}{12}\right\}\)
\(|2x-1|-\frac{1}{2}=\frac{1}{3}\)
\(|2x-1|=\frac{1}{3}+\frac{1}{2}\)
\(|2x-1|=\frac{2+3}{6}\)
\(|2x-1|=\frac{5}{6}\)
\(\Rightarrow2x-1=\frac{5}{6}\) hoặc \(2x-1=-\frac{5}{6}\)
\(TH1:2x-1=\frac{5}{6}\)
\(2x=\frac{5}{6}+1\)
\(2x=\frac{5+6}{6}\)
\(2x=\frac{11}{6}\)
\(x=\frac{11}{6}:2\)
\(x=\frac{11}{6}.\frac{1}{2}\)
\(x=\frac{11}{12}\)
\(TH2:2x-1=-\frac{5}{6}\)
\(2x=-\frac{5}{6}+1\)
\(2x=\frac{-5+6}{6}\)
\(2x=\frac{1}{6}\)
\(x=\frac{1}{6}:2\)
\(x=\frac{1}{6}.\frac{1}{2}\)
\(x=\frac{1}{12}\)
Vậy \(x\in\left\{\frac{11}{12};\frac{1}{12}\right\}\)
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\(\frac{13x-2}{2x+5}=-\frac{27}{5-x}\)ĐK : \(x\ne-\frac{5}{2};5\)
\(\Rightarrow\left(13x-2\right)\left(5-x\right)=-27\left(2x+5\right)\)
\(\Leftrightarrow65x-13x^2-10+2x=-54x-135\)
\(\Leftrightarrow-13x^2+121x+125=0\Leftrightarrow x=10,24...;x=-0,93...\)
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\(\frac{2x-10}{6}=\frac{-27}{5-x}\)
\(\frac{2\left(x-5\right)}{6}=\frac{27}{x-5}\)
\(2\left(x-5\right)^2=27\times6\)
\(2x^2-20x+50-162=0\)
\(2x^2-20x-112=0\)
\(x^2-10x-56=0\)
\(x^2-14x+4x-56=0\)
\(\left(x-14\right)\left(x+4\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-14=0\\x+4=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=14\\x=-4\end{cases}}\)
KL .....
XIN TIICK
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\(3.M=1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{38}}\)
=> \(3M-M=2M=1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{38}}-\frac{1}{3}-\frac{1}{3^2}-...-\frac{1}{3^{39}}\)
=> \(2M=1-\frac{1}{3^{39}}\)
=> \(M=\frac{1}{2}\left(1-\frac{1}{3^{39}}\right)\)
do \(1-\frac{1}{3^{39}}< 1\)
=> \(\frac{1}{2}\left(1-\frac{1}{3^{39}}\right)< \frac{1}{2}.1=\frac{1}{2}\)
Vay \(M< \frac{1}{2}\)
Chuc bn hoc tot !
![](https://rs.olm.vn/images/avt/0.png?1311)
Để B có nghiệm
=> B = 0
=> 2x4 - 8x2 = 0
=> 2x2(x2 - 4) = 0
=> \(\orbr{\begin{cases}2x^2=0\\x^2-4=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=0\\x=\pm2\end{cases}}\)
Vậy x \(\in\left\{0;2;-2\right\}\)là nghiệm của đa thức B
![](https://rs.olm.vn/images/avt/0.png?1311)
(2 x - 3) - (x + 2) = ( x - 2)-3(x - 5)
\(\Leftrightarrow\)2x - 3 - x - 2 = x - 2 - 3x + 15
\(\Leftrightarrow\)x - 5 = 13 - 2x
\(\Leftrightarrow\)3x = 18
\(\Leftrightarrow\)x = 6
Vậy x = 6 là giá trị cần tìm
( 2x - 3 )2 = 16
( 2x - 3 )2 = 42 hoặc (-4)2
=> 2x - 3 = 4 hoặc 2x - 3 = -4
2x = 4+3 2x = -4 + 3
2 x = 7 2x = -1
x = 7/2 x = -1/2
~ Ko bt đúng ko, ko chắc lắm ~
( 2x -3 )2 = 16
( 2x - 3 )2 = 24
2x - 3 = 2
2x =2 + 3
2x = 5
x 5:2
==> x = ko có gt x
k nha bn