15/34+7/21+19/34-1 7/21+2/5
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Bài 1:Tính nhanh có thể
15/34+7/21+19/34-3/1+7/21+2
\(\dfrac{15}{34}+\dfrac{7}{21}+\dfrac{19}{34}-\dfrac{3}{1}+\dfrac{7}{21}+2\)
\(=\left(\dfrac{15}{34}+\dfrac{19}{34}\right)+\left(\dfrac{7}{21}+\dfrac{7}{21}\right)-\left(3-2\right)\)
\(=1-1+\dfrac{14}{21}\)
\(=\dfrac{14}{21}\)
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\(\dfrac{15}{34}+\dfrac{7}{21}+\dfrac{19}{34}-3+\dfrac{7}{21}+2\)
= \(\dfrac{15}{34}+\dfrac{19}{34}+\dfrac{7}{21}+\dfrac{7}{21}-3+2\)
= \(\left(\dfrac{15}{34}+\dfrac{19}{34}\right)+\left(\dfrac{7}{21}+\dfrac{7}{21}\right)-\left(3-2\right)\)
= \(1+\dfrac{2}{3}-1\)
= \(1-1+\dfrac{2}{3}\)
= \(\dfrac{2}{3}\)
GOOD LUCK!
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15/34+7/21+19/34-32/17+2/3
\(\dfrac{15}{34}+\dfrac{7}{21}+\dfrac{19}{34}-\dfrac{32}{17}+\dfrac{2}{3}\)
\(=\left(\dfrac{15}{34}+\dfrac{19}{34}\right)+\dfrac{7}{21}+\dfrac{-32}{17}+\dfrac{2}{3}\)
\(=1+\dfrac{1}{3}+\dfrac{-32}{17}+\dfrac{2}{3}\)
\(=1+\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\dfrac{-32}{17}\)
\(=1+1+\dfrac{-32}{17}\)
\(2+\dfrac{-32}{17}=\dfrac{2}{17}\)
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15/34+7/21+19/34-20/15
=15/34+19/34+1/3-4/3
=1-1
=0
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\(\dfrac{15}{34}-\dfrac{7}{21}+\dfrac{19}{34}-\dfrac{15}{17}-\dfrac{2}{3}\)
\(\dfrac{15}{34}-\dfrac{7}{21}+\dfrac{19}{34}-\dfrac{15}{17}-\dfrac{2}{3}\)
\(=\left(\dfrac{15}{34}+\dfrac{19}{34}\right)-\left(\dfrac{7}{21}+\dfrac{2}{3}\right)-\dfrac{15}{17}\)
\(=1-\left(\dfrac{7}{21}+\dfrac{14}{21}\right)-\dfrac{15}{17}\)
\(=1-1-\dfrac{15}{17}\)
\(=-\dfrac{15}{17}\)
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Câu 1
a) 15/34 + 7/21+ 19/34 -1 15/17+2/3
\(\dfrac{15}{34}+\dfrac{7}{21}+\dfrac{19}{34}-1\dfrac{15}{17}+\dfrac{2}{3}\)
= \(\left(\dfrac{15}{34}+\dfrac{19}{34}\right)+\left(\dfrac{7}{21}+\dfrac{2}{3}\right)-1\dfrac{15}{17}\)
= \(1+\left(\dfrac{7}{21}+\dfrac{14}{21}\right)-1\dfrac{15}{17}\)
= \(1+1-1\dfrac{15}{17}\)
= \(2-1\dfrac{15}{17}\)
= \(\dfrac{2}{17}\)
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15/34 + 7/21 + 19/34 - 20/15 + 3/7
\(\frac{15}{34}+\frac{7}{21}+\frac{19}{34}-\frac{20}{15}+\frac{3}{7}\)
\(=\left(\frac{15}{34}+\frac{19}{34}\right)+\left(\frac{7}{21}-\frac{20}{15}\right)+\frac{3}{7}\)
\(=1+1+\frac{3}{7}=2\frac{3}{7}=\frac{17}{7}\)
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20/34 + 7/21 + 19/34 - 20/15 + 3/7=?
\(Câu 1) \dfrac {15} {34} + \dfrac {7} {21} + \dfrac {19} {34}-1\dfrac {15} {17}+\dfrac {3} {5} Câu 2) \dfrac {(5)^{4}.(20)^{4}} {(24)^{4}.45}\)
Câu 1:
\(=\dfrac{15}{34}+\dfrac{19}{34}-1-\dfrac{15}{17}+\dfrac{1}{3}+\dfrac{3}{5}\)
\(=-\dfrac{15}{17}+\dfrac{14}{15}=\dfrac{13}{255}\)
Câu 2:
\(=\dfrac{5^4\cdot5^4\cdot2^8}{4^4\cdot6^4\cdot3^2\cdot5}=\dfrac{5^7}{6^4\cdot3^2}\)
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15 phần 34 + 7 phần 21 +19 phần 34 - 20 phần 15 +3 phần 7 = ?
\(\frac{15}{34}+\frac{7}{21}+\frac{19}{34}-\frac{20}{15}+\frac{3}{7}\)
\(\frac{15}{34}+\frac{1}{3}+\frac{19}{34}+\left(-\frac{4}{3}\right)+\frac{3}{7}\)
\(\left(\frac{15}{34}+\frac{19}{34}\right)+\left(\frac{1}{3}-\frac{4}{3}\right)+\frac{3}{7}\)
\(1+\left(-1\right)+\frac{3}{7}\)
\(=0+\frac{3}{7}=\frac{3}{7}\)
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\(\frac{15}{34}+\frac{7}{21}+\frac{19}{34}-\frac{20}{15}+\frac{3}{7}\)
\(=\)\(\frac{15}{34}+\frac{1}{3}+\frac{19}{34}+\left(-\frac{4}{3}\right)+\frac{3}{7}\)
\(=\)\(\left(\frac{15}{34}+\frac{19}{34}\right)+\left(\frac{1}{3}-\frac{4}{3}\right)+\frac{3}{7}\)
\(=\)\(1+\left(-1\right)+\frac{3}{7}\)
\(=\)\(0+\frac{3}{7}\)
\(=\)\(\frac{3}{7}\)