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1) \(\frac{2}{3}+x=-\frac{4}{5}\)
\(x=\left(-\frac{4}{5}\right)-\frac{2}{3}\)
\(x=-1\frac{7}{15}\)
Vậy \(x=-1\frac{7}{15}\)
2) \(\frac{2}{5}-x=-\frac{1}{3}\)
\(x=\frac{2}{5}-\left(-\frac{1}{3}\right)\)
\(x=\frac{11}{15}\)
Vậy \(x=\frac{11}{15}\)
3) \(1-\frac{x}{3}=1\frac{1}{2}\)
\(\frac{x}{3}=1-1\frac{1}{2}\)
\(\frac{x}{3}=-\frac{1}{2}\)
\(\Rightarrow x=\frac{\left(-1\right)\cdot3}{2}\)
\(x=-1\frac{1}{2}\)
4) \(1-\left(\frac{2x}{3}+2\right)=-1\)
\(\frac{2x}{3}+2=1-\left(-1\right)\)
\(\frac{2x}{3}+2=2\)
\(\frac{2x}{3}=2-2\)
\(\frac{2x}{3}=0\)
\(\Rightarrow x=0\)
Vậy \(x=0\)
giúp mik nha chiều này 6:00 mik nộp rồi
ai nhanh mik sẽ k cho 3 k
\(2\frac{3}{5}x-\frac{1}{7}=1\frac{9}{35}\)
\(\frac{13}{5}x=\frac{44}{35}+\frac{1}{7}\)
\(\frac{13}{5}x=\frac{7}{5}\)
\(x=\frac{7}{5}:\frac{13}{5}\\ x=\frac{7}{13}\)
\(=-2.\frac{2}{3}.\frac{1}{3}:\left(\frac{-1}{6}+0,5\right)-\left(-2009^0\right)-\left(-2\right)^2\)
\(=\frac{4}{3}.\frac{1}{3}:\left(\frac{-1}{6}+\frac{1}{2}\right)-1.4\)
\(=\frac{4}{3}.\frac{1}{3}+4\)
\(=4+4\)
\(=8\)
Mấy câu trên dễ , bạn có thể tự làm được
Chứng minh \(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{10^2}< 1\)
Đặt \(A=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{10^2}\)
Ta có : \(\frac{1}{2^2}=\frac{1}{2\cdot2}< \frac{1}{1\cdot2}\)
\(\frac{1}{3^2}=\frac{1}{3\cdot3}< \frac{1}{2\cdot3}\)
\(\frac{1}{4^2}=\frac{1}{4\cdot4}< \frac{1}{3\cdot4}\)
...
\(\frac{1}{10^2}=\frac{1}{10\cdot10}< \frac{1}{9\cdot10}\)
=> \(A=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{10^2}< \frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{9\cdot10}\)
=> \(A=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{10^2}< \frac{1}{1}-\frac{1}{10}\)
=> \(A=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{10^2}< \frac{9}{10}\)
Lại có : \(\frac{9}{10}< 1\)
=> \(A< \frac{9}{10}< 1\)
=> \(A< 1\left(đpcm\right)\)
1.
A=\(\frac{-5x+-5y+-5z}{21}=\frac{-5\left(x+y+z\right)}{21}=\frac{-5}{21}.x+y+z\)
A= -z+z=0
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1. \(\frac{25}{100}x+x-\frac{1}{5}x=\frac{1}{5}\)
\(\Leftrightarrow\frac{1}{4}x+x-\frac{1}{5}x=\frac{1}{5}\)
\(\Leftrightarrow\left(\frac{1}{4}+1-\frac{1}{5}\right)x=\frac{1}{5}\)
\(\Leftrightarrow\frac{21}{20}x=\frac{1}{5}\)
\(\Leftrightarrow x=\frac{1}{5}:\frac{21}{20}\)
\(\Leftrightarrow x=\frac{4}{21}\)
Chút nữa tớ làm cho
2. \(\frac{2}{3}x-\frac{1}{2}x=\frac{3}{5}\)
\(\Leftrightarrow\frac{1}{6}x=\frac{3}{5}\)
\(\Leftrightarrow x=\frac{3}{5}:\frac{1}{6}\)
\(\Leftrightarrow x=\frac{18}{5}\)
3. \(\frac{2}{5}x-1\frac{1}{2}x+x=\frac{1}{3}\)
\(\Leftrightarrow\left(\frac{2}{5}-1\frac{1}{2}+1\right)x=\frac{1}{3}\)
\(\Leftrightarrow-\frac{1}{10}x=\frac{1}{3}\)
\(\Leftrightarrow x=-\frac{10}{3}\)
4. \(\left(x+\frac{2}{7}\right)\left(\frac{2}{3}-2x\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x+\frac{2}{7}=0\\\frac{2}{3}-2x=0\end{array}\right.\) \(\Leftrightarrow\left[\begin{array}{nghiempt}x=-\frac{2}{7}\\x=\frac{1}{3}\end{array}\right.\)
1) \(25\%x+x-\frac{1}{5}x=\frac{1}{5}\)
\(\Rightarrow\frac{1}{4}x+x-\frac{1}{5}x=\frac{1}{5}\)
\(\Rightarrow x.\left(\frac{1}{4}+1-\frac{1}{5}\right)=\frac{1}{5}\)
\(\Rightarrow x.\frac{21}{20}=\frac{1}{5}\)
\(\Rightarrow x=\frac{1}{5}:\frac{21}{20}\)
\(\Rightarrow x=\frac{4}{21}\)
2) \(\frac{2}{3}x-\frac{1}{2}x=\frac{3}{5}\)
\(\Rightarrow x.\left(\frac{2}{3}-\frac{1}{2}\right)=\frac{3}{5}\)
\(\Rightarrow x.\frac{1}{6}=\frac{3}{5}\)
\(\Rightarrow x=\frac{3}{5}:\frac{1}{6}\)
\(\Rightarrow x=\frac{18}{5}\)
3) \(\frac{2}{3}x-1\frac{1}{2}x+x=\frac{1}{3}\)
\(\Rightarrow x.\left(\frac{2}{5}-1\frac{1}{2}+1\right)=\frac{1}{3}\)
\(\Rightarrow x.\left(-\frac{1}{10}\right)=\frac{1}{3}\)
\(\Rightarrow x=\frac{1}{3}:\left(-\frac{1}{10}\right)\)
\(\Rightarrow x=-\frac{10}{3}\)
4) \(\left(x+\frac{2}{7}\right).\left(\frac{2}{3}-2x\right)=0\)
\(\Rightarrow\left[\begin{array}{nghiempt}x+\frac{2}{7}=0\\\frac{2}{3}-2x=0\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=-\frac{2}{7}\\x=\frac{1}{3}\end{array}\right.\)
1 . 25%x + x - \(\frac{1}{5}\)x = \(\frac{1}{5}\)
\(\frac{1}{4}\)x + 1x - \(\frac{1}{5}\)x = \(\frac{1}{5}\)
x ( \(\frac{1}{4}+1-\frac{1}{5}\) ) = \(\frac{1}{5}\)
x \(\frac{21}{20}\)= \(\frac{1}{5}\)
x = \(\frac{1}{5}:\frac{21}{20}\)
x = \(\frac{4}{21}\)
2 . \(\frac{2}{3}x-\frac{1}{2}x=\frac{3}{5}\)
\(\left(\frac{2}{3}-\frac{1}{2}\right)x=\frac{3}{5}\)
\(\frac{1}{6}x=\frac{3}{5}\)
\(x=\frac{3}{5}:\frac{1}{6}\)
\(x=\frac{18}{5}\)
Mik ngại viết theo kiểu phân số nên bạn thông cảm nha :
2/5x - 1 1/2x + x = 1/3
2/5x - 3/2x + 1x = 1/3
( 2/5 - 3/2 + 1 )x = 1/3
-1/10x = 1/3
x = 1/3 : -1/10
x = 13/30
4 . ( x + 2/7 ) . ( 2/3 - 2x ) = 0
=> x + 2/7 = 0 hoặc 2/3 - 2x = 0
Ta xét : x + 2/7 = 0
x = 0 - 2/7
x = -2/7
Ta xét : 2/3 - 2x = 0
2x = 2/3 - 0
2x = 2/3
x = 2/3 : 2
x = 1/3
1. \(25\%x+x-\frac{1}{5}x=\frac{1}{5}\)
\(x\left(\frac{1}{4}+1-\frac{1}{5}\right)=\frac{1}{5}\)
\(\frac{21x}{20}=\frac{1}{5}\)
\(\frac{21x}{20}=\frac{4}{20}\)
\(21x=4\Rightarrow x=\frac{4}{21}\)
2. \(\frac{2}{3}x-\frac{1}{2}x=\frac{3}{5}\)
\(x\left(\frac{2}{3}-\frac{1}{2}\right)=\frac{3}{5}\)
\(\frac{x}{6}=\frac{3}{5}\)
\(\frac{5x}{30}=\frac{18}{30}\)
\(5x=18\Rightarrow x=\frac{18}{5}\)
3. \(\frac{2}{5}x-1\frac{1}{2}x+x=\frac{1}{3}\)
\(x\left(\frac{2}{5}-1\frac{1}{2}+1\right)=\frac{1}{3}\)
\(\frac{-x}{10}=\frac{1}{3}\)
\(\frac{-3x}{30}=\frac{10}{30}\)
\(-3x=10\Rightarrow x=-\frac{10}{3}\)
4. \(\left(x+\frac{2}{7}\right)\left(\frac{2}{3}-2x\right)=0\)
*\(x+\frac{2}{7}=0\Rightarrow x=-\frac{2}{7}\)
*\(\frac{2}{3}-2x=0\Rightarrow x=\frac{1}{3}\)
Vậy \(x=-\frac{2}{7};x=\frac{1}{3}\)
làm sai rồi mà có đứa tick không biết đứa nào khôn dễ sợ