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\(\left(\dfrac{1}{4}+\dfrac{1}{7}\right)\times\dfrac{1}{3}\\ =\left(\dfrac{7}{28}+\dfrac{4}{28}\right)\times\dfrac{1}{3}\\ =\dfrac{11}{28}\times\dfrac{1}{3}\\ =\dfrac{11}{84}\)
a) \(\left(\frac{1}{5}+\frac{3}{5}\right)\times\frac{1}{4}\)
\(=\frac{4}{5}\times\frac{1}{4}\)
\(=\frac{4}{20}=\frac{1}{5}\)
\(\left(\frac{1}{5}+\frac{3}{5}\right)\times\frac{1}{4}=\frac{1}{5}\times\frac{1}{4}+\frac{3}{5}\times\frac{1}{4}\)
\(=\frac{1}{20}+\frac{3}{20}\)
\(=\frac{4}{20}=\frac{1}{5}\)
b) \(\left(\frac{7}{9}-\frac{2}{9}\right)\times\frac{3}{2}\)
\(=\frac{5}{9}\times\frac{3}{2}\)
\(=\frac{15}{18}=\frac{5}{6}\)
\(\left(\frac{7}{9}-\frac{2}{9}\right)\times\frac{3}{2}=\frac{7}{9}\times\frac{3}{2}-\frac{2}{9}\times\frac{3}{2}\)
\(=\frac{21}{18}-\frac{6}{18}\)
\(=\frac{15}{18}=\frac{5}{6}\)
c) \(\left(\frac{11}{13}-\frac{9}{13}\right)\times\frac{39}{21}\)
\(=\frac{2}{13}\times\frac{39}{21}\)
\(=\frac{78}{273}=\frac{2}{7}\)
\(\left(\frac{11}{13}-\frac{9}{13}\right)\times\frac{39}{21}=\frac{11}{13}\times\frac{39}{21}-\frac{9}{13}\times\frac{39}{21}\)
\(=\frac{429}{273}-\frac{351}{273}\)
\(=\frac{78}{273}=\frac{2}{7}\)
a,\(\left(\frac{1}{5}+\frac{3}{5}\right)x\frac{1}{4}\)
=\(\frac{4}{5}x\frac{1}{4}\)
=\(\frac{4}{20}\)
=\(\frac{1}{5}\)
,\(\left(\frac{1}{5}+\frac{3}{5}\right)x\frac{1}{4}\)
=\(\frac{4}{5}x\frac{1}{4}\)
=\(\frac{4x1}{5x4}\)
=\(\frac{1x1}{5x1}\)
=\(\frac{1}{5}\)
a: =8/15x1/4=2/15
b: \(=\dfrac{5}{3}\cdot\dfrac{4}{5}\cdot\dfrac{6}{7}=\dfrac{24}{21}=\dfrac{8}{7}\)
c: \(=\dfrac{2}{5}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)=\dfrac{2}{5}\)
C1 : 11/28 x 1/3 =11/84
C2 : 1/4 x1/3 + 1/7 x 1/3 = 11/84
C1 : 3/28 x 1/3 =1/28
C2 1/4 x1/3 - 1/7 x 1/3 =1/28
a,3/5+4/7+2/5+1/7+2/7
= (4/7+1/7+2/7)+(3/5+4/5)
=7/7+5/5
=1+1
=2
b, 1/3+1/6+4/3+2/6+2/3+5/6
=(1/3+4/3+2/3)+(1/6+5/6+2/6)
=7/3+8/6
=7/3+4/3
=11/3
a) Cách 1 : (3/4 + 1/2) x 5/7
= 5/4 x 5/7
= 25/28
Cách 2 : (3/4 + 1/2) x 5/7
= 3/4 x 5/7 + 1/2 x 5/7
= 15/28 + 5/14
= 25/28
b) Cách 1 : 5/7 x 13/21 + 2/7 x 13/21
= 65/147 + 26/147
= 13/21
Cách 2 : 5/7 x 13/21 + 2/7 x 13/21
= (5/7 + 2/7) x 13/21
= 1 x 13/21
= 13/21
câu c tự làm
Bài 5:
a: =1/3+2/5
=5/15+6/15
=11/15
b: =6/21+12/21=18/21=6/7
c: =16/24+10/24
=26/24
=13/12
d: =4/12+3/12+10/12
=17/12
e: =19/24-9/24
=10/24
=5/12
f: =8/9-3/9=5/9
g: =9/3+1/3=10/3
k: =15/24+42/24+14/24
=71/24
2 3/7x1/2 1/2x 3/7 +1/3 =2+ 1/3
=6/3
đúng thì
thank you !