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MH
14 tháng 9 2021
a)\(\dfrac{2}{3}.\dfrac{4}{5}+\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}+\dfrac{1}{3}\right).\dfrac{4}{5}=1.\dfrac{4}{5}=\dfrac{4}{5}\)
b)\(\dfrac{2}{3}.\dfrac{4}{5}-\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}-\dfrac{1}{3}\right).\dfrac{4}{5}=\dfrac{1}{3}.\dfrac{4}{5}=\dfrac{4}{15}\)
14 tháng 9 2021
a) \(\dfrac{2}{3}\times\dfrac{4}{5}+\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}+\dfrac{1}{3}\right)=\dfrac{4}{5}\times1=\dfrac{4}{5}\)
b) \(\dfrac{2}{3}\times\dfrac{4}{5}-\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}-\dfrac{1}{3}\right)=\dfrac{4}{5}\times\dfrac{1}{3}=\dfrac{4}{15}\)
c) \(\dfrac{1}{2}:\dfrac{3}{4}+\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}+\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\times\left(\dfrac{1}{2}+\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{2}{3}=\dfrac{8}{9}\)
d) \(\dfrac{1}{2}:\dfrac{3}{4}-\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}-\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{1}{3}=\dfrac{4}{9}\)
KV
4 tháng 11 2023
Bài 1
a) 3 2/5 - 1/2
= 17/5 - 1/2
= 34/10 - 5/10
= 29/10
b) 4/5 + 1/5 × 3/4
= 4/5 + 3/20
= 16/20 + 3/20
= 19/20
c) 3 1/2 × 1 1/7
= 7/2 × 8/7
= 4
d) 4 1/6 : 2 1/3
= 25/6 : 7/3
= 25/14
KV
4 tháng 11 2023
Bài 2
a) 3 × 1/2 + 1/4 × 1/3
= 3/2 + 1/12
= 18/12 + 1/12
= 19/12
b) 1 4/5 - 2/3 : 2 1/3
= 9/5 - 2/3 : 7/3
= 9/5 - 2/7
= 63/35 - 10/35
= 53/35
11 tháng 9 2017
a) x + 1/15 = 1/3 - 1/4 = 4/12 - 3/12 = 1/12.
=> x = 1/12 - 1/15 = 5/60 - 4/60 = 1/60.
b) x - 5/12 = 1/3 + 1/4 = 4/12 + 3/12 = 7/12.
=> x = 7/12 + 5/12 = 1
c) x x 2/7 = 3/4 x 4/15 = 1/5
=> x = 1/5 : 2/7 = 1/5 x 7/2 = 7/10
d) x : 3/8 = 4/3 : 3/6 = 4/3 x 2 = 8/3
=> x = 8/3 x 3/8 = 1
DC
3
9 tháng 8 2023
a) \(x+2\dfrac{3}{4}=5\dfrac{2}{3}\)
\(x+\dfrac{11}{4}=\dfrac{17}{3}\)
\(x=\dfrac{17}{3}-\dfrac{11}{4}\)
\(x=\dfrac{35}{12}\)
b) \(x-1\dfrac{4}{5}=3\dfrac{2}{7}\)
\(x-\dfrac{9}{5}=\dfrac{23}{7}\)
\(x=\dfrac{23}{7}+\dfrac{9}{5}\)
\(x=\dfrac{178}{35}\)
c) \(x\times3\dfrac{1}{2}=4\dfrac{3}{4}\)
\(x\times\dfrac{7}{2}=\dfrac{19}{4}\)
\(x=\dfrac{19}{4}\div\dfrac{7}{2}\)
\(x=\dfrac{19}{14}\)
d) \(x\div2\dfrac{2}{3}=4\dfrac{1}{3}\)
\(x\div\dfrac{8}{3}=\dfrac{13}{3}\)
\(x=\dfrac{13}{3}\times\dfrac{8}{3}\)
\(x=\dfrac{104}{9}\)
ND
Nguyễn Đức Trí
VIP
9 tháng 8 2023
a) \(...=x+\dfrac{11}{3}=\dfrac{17}{3}\Rightarrow x=\dfrac{17}{3}-\dfrac{11}{3}=\dfrac{6}{3}=2\)
b) \(...\Rightarrow x-\dfrac{9}{5}=\dfrac{23}{7}\Rightarrow x=\dfrac{23}{7}+\dfrac{9}{5}=\dfrac{115}{35}+\dfrac{36}{35}=\dfrac{151}{35}\)
c) \(...\Rightarrow x.\dfrac{7}{2}=\dfrac{19}{4}\Rightarrow x=\dfrac{19}{4}:\dfrac{7}{2}\Rightarrow x=\dfrac{19}{4}.\dfrac{2}{7}=\dfrac{19}{14}\)
d) \(...\Rightarrow x:\dfrac{8}{3}=\dfrac{13}{3}\Rightarrow x=\dfrac{13}{3}.\dfrac{8}{3}=\dfrac{124}{9}\)
13 tháng 9 2017
a)1/3+1/4+2/3+3/4
=(1/3+2/3)+(1/4+3/4)
=1+1
=2.
b)1/2+1/3-1/5+1/6
=(1/2+1/3+1/6)-1/5
=1-1/5
=4/5
c)2/3x4/5+1/3x4/5
=4/5x(2/3+1/3)
=4/5x1
=4/5
d)2/3x4/5-1/3x4/5
=4/5x(2/3-1/3)
=4/5x1/3
=4/15
DA
2
5 tháng 6 2023
=>3x(1-1/6)=3/4
=>3x=3/4:5/6=3/4*6/5=18/20=9/10
=>x=3/10
5 tháng 6 2023
Đề là \(3x\left(\dfrac{1}{1}\times\dfrac{1}{2}+\dfrac{1}{2}\times\dfrac{1}{3}+\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{4}\times\dfrac{1}{5}+\dfrac{1}{5}\times\dfrac{1}{6}\right)=\dfrac{3}{4}?\)
`3x (1/1 \times 1/2 + 1/2 \times 1/3 + 1/3 \times 1/4 + 1/4 \times 1/5 + 1/5 \times 1/6) = 3/4`
\(3x\left(\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}\right)=\dfrac{3}{4}\)
\(3x\left(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}\right)=\dfrac{3}{4}\)
\(3x\left(1-\dfrac{1}{6}\right)=\dfrac{3}{4}\)
\(3x\times\dfrac{5}{6}=\dfrac{3}{4}\)
`3x=3/4 \div 5/6`
`3x = 9/10`
`x = 9/10 \div 3`
`x = 3/10.`
HA
2
3 tháng 10 2023
\(\dfrac{2}{7}:\dfrac{1}{4}-\dfrac{1}{7}=\dfrac{2}{7}x\dfrac{4}{1}-\dfrac{1}{7}=\dfrac{8}{7}-\dfrac{1}{7}=\dfrac{7}{7}=1\)
\(\dfrac{7}{11}x0+\dfrac{5}{9}:\dfrac{1}{2}=0+\dfrac{5}{9}x\dfrac{2}{1}=\dfrac{10}{9}\)
\(\left(\dfrac{3}{7}+\dfrac{1}{4}\right):\dfrac{3}{4}=\left(\dfrac{12}{28}+\dfrac{7}{28}\right)x\dfrac{4}{3}=\dfrac{19}{28}x\dfrac{4}{3}=\dfrac{19}{21}\)
\(\dfrac{4}{3}x\dfrac{1}{2}+\dfrac{7}{2}:\dfrac{1}{4}=\dfrac{4}{6}+\dfrac{7}{2}x\dfrac{4}{1}=\dfrac{2}{3}+\dfrac{14}{1}=\dfrac{2}{3}+14=14\dfrac{2}{3}=\dfrac{44}{3}\)
\(x-\dfrac{1}{4}=1+\dfrac{3}{4}\)
\(x-\dfrac{1}{4}=\dfrac{7}{4}\)
\(x=\dfrac{7}{4}+\dfrac{1}{4}\)
\(x=\dfrac{8}{4}\)
\(x=2\)
Vậy \(x=2\)
x - 1/4=1+3/4
X - 1/4 = 7/4
X = 7/4+1/4
X = 2