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ND
3
VT
6 tháng 3 2023
\(a,\dfrac{9}{17}+\dfrac{15}{4}=\dfrac{36}{68}+\dfrac{255}{68}=\dfrac{291}{68}\\ b,\dfrac{19}{121}-\dfrac{1}{11}=\dfrac{19}{121}-\dfrac{11}{121}=\dfrac{8}{121}\\ c,\dfrac{4}{15}+3=\dfrac{4}{15}+\dfrac{45}{15}=\dfrac{49}{15}\\ d,3-\dfrac{5}{9}=\dfrac{27}{9}-\dfrac{5}{9}=\dfrac{22}{9}\)
NK
6 tháng 3 2023
\(a,\dfrac{9}{17}+\dfrac{15}{4}=\dfrac{36}{68}+\dfrac{255}{68}=\dfrac{291}{68}\)
\(b,\dfrac{19}{121}-\dfrac{1}{11}=\dfrac{19}{121}-\dfrac{11}{121}=\dfrac{8}{121}\)
\(c,\dfrac{4}{15}+3=\dfrac{4}{15}+\dfrac{3}{1}=\dfrac{4}{15}+\dfrac{45}{15}=\dfrac{49}{15}\)
\(d,3-\dfrac{5}{9}=\dfrac{3}{1}-\dfrac{5}{9}=\dfrac{27}{9}-\dfrac{5}{9}=\dfrac{22}{9}\)
9 tháng 3 2022
a: \(=\dfrac{21}{11}+\dfrac{12}{11}+\left(-\dfrac{9}{19}-\dfrac{3}{19}-\dfrac{6}{19}\right)=3-\dfrac{18}{19}=\dfrac{39}{19}\)
b: \(=\dfrac{2}{3}+\dfrac{4}{3}+\dfrac{3}{4}+\dfrac{7}{4}+\dfrac{4}{5}+\dfrac{16}{5}=2+4+\dfrac{5}{2}=6+\dfrac{5}{2}=\dfrac{17}{2}\)
29 tháng 1
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
=>\(\dfrac{15}{19}\cdot\dfrac{38}{5}>\dfrac{15}{16}:\dfrac{3}{8}\)
VN
17 tháng 3 2022
a, \(\frac{2}{5}\)x ( \(\frac{3}{7}\)+\(\frac{4}{7}\))
= \(\frac{2}{5}\)x \(\frac{7}{7}\)
= \(\frac{2}{5}\)x 1
= \(\frac{2}{5}\)
b, \(\frac{47}{19}\) :\(\frac{15}{32}\) - \(\frac{47}{19}\) :\(\frac{15}{17}\)
= \(\frac{47}{19}\) × \(\frac{32}{15}\) - \(\frac{47}{19}\) × \(\frac{17}{15}\)
= \(\frac{47}{19}\) × (\(\frac{32}{15}\)-\(\frac{17}{15}\))
= \(\frac{47}{19}\) × 1
= \(\frac{47}{19}\)
H
6 tháng 3 2023
`1/3 + 1/5 -1/4`
`= 5/15 + 3/15 -1/4`
`= 8/15 -1/4`
`= 17/60`
__
`7/8 -(1/4 + 2/5)`
`= 7/8-1/4 - 2/5`
`= 7/8 - 2/8 -2/5`
`= 5/8 -2/5`
`= 9/40`
__
`5/11-(3/5 -6/11)`
`= 5/11 -3/5 +6/11`
`= (5/11 + 6/11)-3/5`
`= 1 -3/5`
`= 5/5-3/5`
`=2/5`
__
`5/7 - ( 19/35 - 6/15)`
`= 5/7 - 19/35 + 6/15`
`= 25/35 -19/35 + 6/15`
`=6/35 +6/15`
`=4/7`
A/B + 3/5 = 19/15
\(\frac{A}{B}=\frac{19}{15}-\frac{3}{5}\)
\(\frac{A}{B}=\frac{19}{15}-\frac{9}{15}=\frac{10}{15}=\frac{2}{3}\)