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b. \(\dfrac{4.2.3.5.2.6.2.5.3}{4.3.4.5.6.4.5.6}=\dfrac{1}{4}\)
c. \(\dfrac{17.2.101.2005}{17.2.101.2.2005}=\dfrac{1}{2}\)
d. \(\dfrac{2.3.4.2.11.13.17}{3.11.4.4.17.13.2}=\dfrac{1}{2}\)
a)\(\dfrac{4\times6\times10\times12\times15}{4\times12\times5\times24\times30}=\dfrac{2}{2\times2\times2}=\dfrac{2}{8}=\dfrac{1}{4}\)
b)\(\dfrac{34\times101\times2005}{17\times202\times4010}=\dfrac{2}{2\times2}=\dfrac{2}{4}=\dfrac{1}{2}\)
c)\(\dfrac{6\times8\times11\times13\times17}{33\times16\times17\times26}=\dfrac{6}{3\times2\times2}=\dfrac{1}{2}\)
a) Viết thương của mỗi phép chia sau dưới dạng phân số (theo mẫu).
13 : 17 = \(\dfrac{13}{17}\)
21 : 11 = \(\dfrac{22}{11}\)
40 : 51 = \(\dfrac{40}{51}\)
72 : 25 = \(\dfrac{72}{25}\)
b) Viết (theo mẫu)
34 : 17 = \(\dfrac{34}{17}\) = 2
20 : 5 =\(\dfrac{20}{5}\) = 4
42 : 42 = \(\dfrac{42}{42}\) = 1
0 : 6 = \(\dfrac{0}{6}\) = 0
\(\frac{15}{34}-\frac{5}{17}+\frac{19}{34}-\frac{12}{17}\)
\(=\left(\frac{15}{34}+\frac{19}{34}\right)-\left(\frac{5}{17}+\frac{12}{17}\right)\)
\(=1-1=0\)
\(\frac{15}{34}-\frac{5}{17}+\frac{19}{34}-\frac{12}{17}\)
\(=\left(\frac{15}{34}+\frac{19}{34}\right)-\left(\frac{5}{17}+\frac{12}{17}\right)\)
\(=\frac{34}{34}-\frac{17}{17}\)
\(=1-1\)
\(=0\)
`3/7+2/5+4/7`
`=(3/7+4/7)+2/5`
`=1+2/5`
`=5/5+2/5`
`=7/5`
`20/34+4/9+7/17`
`=(20/34+7/17)+4/9`
`=(20/34+14/34)+4/9`
`=34/34+4/9`
`=1+4/9`
`=9/9+4/9`
`=13/9`
`48xx2+96+48xx6`
`=48xx2+48xx2+48xx6`
`=48xx(2+2+6)`
`=48xx10`
`=480`
câu thứ hai thì làm như này em nhé:
\(\dfrac{20}{34}\) + \(\dfrac{4}{9}\) + \(\dfrac{7}{17}\)
= (\(\dfrac{20}{34}\) + \(\dfrac{7}{17}\)) + \(\dfrac{4}{9}\)
= (\(\dfrac{10}{17}\) + \(\dfrac{7}{17}\)) + \(\dfrac{4}{9}\)
= 1 + \(\dfrac{4}{9}\)
= \(\dfrac{13}{9}\)
a: \(\dfrac{5}{3}\cdot\dfrac{7}{10}=\dfrac{5}{10}\cdot\dfrac{7}{3}=\dfrac{14}{3}>2\)
\(\dfrac{5}{7}:\dfrac{7}{10}=\dfrac{5}{7}\cdot\dfrac{10}{7}=\dfrac{50}{49}< 2\)
=>\(\dfrac{5}{3}\cdot\dfrac{7}{10}>\dfrac{5}{7}:\dfrac{7}{10}\)
b: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)
\(\dfrac{8}{9}:\dfrac{4}{3}=\dfrac{8}{9}\cdot\dfrac{3}{4}=\dfrac{8}{4}\cdot\dfrac{3}{9}=\dfrac{2}{3}\)
Do đó: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{8}{9}:\dfrac{4}{3}\)
c: \(\dfrac{5}{11}\cdot\dfrac{33}{15}=\dfrac{5}{15}\cdot\dfrac{33}{11}=\dfrac{3}{3}=1\)
\(\dfrac{6}{17}\cdot\dfrac{34}{25}=\dfrac{34}{17}\cdot\dfrac{6}{25}=2\cdot\dfrac{6}{25}=\dfrac{12}{25}< 1\)
=>\(\dfrac{5}{11}\cdot\dfrac{33}{15}>\dfrac{6}{17}\cdot\dfrac{34}{25}\)
d: \(\dfrac{15}{19}\cdot\dfrac{38}{5}=\dfrac{15}{5}\cdot\dfrac{38}{19}=3\cdot2=6\)
\(\dfrac{15}{16}:\dfrac{3}{8}=\dfrac{15}{16}\cdot\dfrac{8}{3}=\dfrac{15}{3}\cdot\dfrac{8}{16}=\dfrac{5}{2}\)<6
=>\(\dfrac{15}{19}\cdot\dfrac{38}{5}>\dfrac{15}{16}:\dfrac{3}{8}\)
$#Shả$
`A)=5/17xx(15/34+19/34)`
`=5/17xx1=5/17`
`B)=(13/12+7/12)+1/3`
`=5/3+1/3=2`
\(\frac{12.15.17}{6.34.45}\)
\(=\frac{12.15.17}{6.2.17.15.3}\)
\(=\frac{12.15.17}{12.17.15.3}\)
\(=\frac{1}{3}\)
a) 3/7+5/2+4/7
=(3/7+4/7)+5/2
=1+5/2
=7/2
b)6/8+4/5+1/4
=(6/8+1/4)+4/5
=1+4/5
=9/5
đến đó thôi mệt quá
\(\dfrac{5}{17}\) + \(\dfrac{6}{34}\)
= \(\dfrac{5}{17}\) + \(\dfrac{3}{17}\)
= \(\dfrac{8}{17}\)
8/17