(7-X)/2 cộng 2/3.(x-7).(x-3
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\(\frac{7-x}{2}+\frac{2}{3}.\left(x-7\right)\left(x-3\right)=0\)
\(\Leftrightarrow\frac{x-7}{-2}+\frac{2\left(x-7\right)}{3}\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-7\right)\left[\frac{-1}{2}+\frac{2}{3}\left(x-3\right)\right]=0\)
\(\Leftrightarrow\left(x-7\right)\left(\frac{-1}{2}+\frac{2x}{3}-2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-7=0\\\frac{-1}{2}+\frac{2x}{3}-2=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=7\\-\frac{5}{2}+\frac{2x}{3}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=7\\\frac{2x}{3}=\frac{5}{2}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=7\\x=\frac{15}{4}\end{cases}}}\)
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Bài 1:
a: \(\dfrac{25}{42}-\dfrac{20}{63}=\dfrac{75-40}{126}=\dfrac{35}{126}=\dfrac{5}{18}\)
b: \(\dfrac{9}{20}-\dfrac{13}{75}-\dfrac{1}{6}=\dfrac{135}{300}-\dfrac{52}{300}-\dfrac{50}{300}=\dfrac{33}{300}=\dfrac{11}{100}\)
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6 2/7 + 7 3/5 + 8 6/9 + 9 1/4 + 2/5 + 5/7 + 1/3 x 3/4 + 1967
= 44/7 + 38/5 + 78/9 + 37/4 + 2/5 + 5/7 + 1/3 + 1967
= ( 44/7 + 5/7 ) + ( 38/5 + 2/5 ) + ( 26/3 + 1/3 ) + ( 37/4 + 3/4 ) +1967
= 7 + 8 + 9 + 10 + 1967
= 15 + 9 + 10 + 1967
= 24 + 10 + 1967
= 34 + 1967
= 2001
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\(\left(x+\frac{2}{7}\right)+\frac{1}{3}=-2\)
\(x+\frac{13}{21}=-2\)
\(x=-2-\frac{13}{21}\)
\(x=\frac{-55}{21}\)
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