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LT
0
15 tháng 8 2023
a: \(=\dfrac{4+15}{20}\cdot\dfrac{1}{2}=\dfrac{19}{20}\cdot\dfrac{1}{2}=\dfrac{19}{40}\)
b: \(=\dfrac{13}{20}-\dfrac{1}{4}+\dfrac{5}{20}=\dfrac{18}{20}-\dfrac{1}{4}\)
\(=\dfrac{9}{10}-\dfrac{1}{4}=\dfrac{18}{20}-\dfrac{5}{20}=\dfrac{13}{20}\)
OD
1
18 tháng 1
a: \(\dfrac{16}{15}\cdot\dfrac{-5}{14}\cdot\dfrac{54}{24}\cdot\dfrac{56}{21}\)
\(=\dfrac{16}{24}\cdot\dfrac{-5}{15}\cdot\dfrac{54}{21}\cdot\dfrac{56}{14}\)
\(=\dfrac{2}{3}\cdot\dfrac{-1}{3}\cdot\dfrac{18}{7}\cdot4\)
\(=\dfrac{-2\cdot2\cdot4}{7}=-\dfrac{16}{7}\)
b: \(\dfrac{7}{3}\cdot\dfrac{-5}{2}\cdot\dfrac{15}{21}\cdot\dfrac{4}{-5}\)
\(=\dfrac{7}{3}\cdot\dfrac{5}{7}\cdot\dfrac{5}{2}\cdot\dfrac{4}{5}\)
\(=\dfrac{5}{3}\cdot\dfrac{4}{2}=\dfrac{5}{3}\cdot2=\dfrac{10}{3}\)
c: \(\left(-\dfrac{2}{5}+\dfrac{1}{3}\right)\left(\dfrac{3}{2}-\dfrac{3}{7}\right)\)
\(=\dfrac{-2\cdot5+3}{15}\cdot\dfrac{3\cdot7-3\cdot2}{14}\)
\(=\dfrac{-7}{15}\cdot\dfrac{15}{14}=\dfrac{-7}{14}=-\dfrac{1}{2}\)
d: \(\left(\dfrac{1}{2}-\dfrac{1}{3}\right)\left(5-\dfrac{1}{4}\right)\)
\(=\dfrac{3-2}{6}\cdot\dfrac{20-1}{4}\)
\(=\dfrac{1}{6}\cdot\dfrac{19}{4}=\dfrac{19}{24}\)
e: \(\left(\dfrac{4}{5}\right)^2=\dfrac{4^2}{5^2}=\dfrac{16}{25}\)
HP
3
T
13 tháng 8 2023
a) \(\dfrac{6}{7}+\dfrac{7}{8}=\dfrac{48}{56}+\dfrac{49}{56}=\dfrac{97}{56}\)
b) \(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\)
c) \(\dfrac{2}{3}.\dfrac{4}{9}=\dfrac{8}{27}\)
d) \(\dfrac{1}{5}:\dfrac{2}{7}=\dfrac{1}{5}.\dfrac{7}{2}=\dfrac{7}{10}\)
13 tháng 8 2023
a: =48/56+49/56
=97/56
b: =12/15-10/15
=2/15
c: =(2*4)/(3*9)=8/27
d: =1/5*7/2=7/10
HP
2
H
13 tháng 8 2023
`x + 2 3/4 = 5 2/3`
`=> x + 11/4 = 17/3`
`=> x= 17/3 -11/4`
`=>x=35/12`
__
`x - 1 4/5 = 3 2/7`
`=> x- 9/5 = 23/7`
`=> x= 23/7 +9/5`
`=>x=178/35`
__
`x xx 3 1/2 =4 3/4`
`=> x xx 7/2 =19/4`
`=> x= 19/4 : 7/2`
`=> x= 19/4 xx 2/7`
`=> x= 19/14`
__
`x : 2 2/3 = 4 1/3`
`=> x : 8/3 = 13/3`
`=> x= 13/3 xx 8/3`
`=>x=104/9`
13 tháng 8 2023
a: =>x+11/4=17/3
=>x=17/3-11/4=68/12-33/12=35/12
b: =>x-9/5=23/7
=>x=23/7+9/5=178/35
c: =>x*7/2=4,75
=>x=19/4:7/2=19/14
d: =>x:8/3=13/3
=>x=13/3*8/3=104/9
