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\(\dfrac{2}{5}+\dfrac{2}{3}+\dfrac{2}{4}\)
= \(\dfrac{24}{60}\) + \(\dfrac{40}{60}\) + \(\dfrac{30}{60}\)
= \(\dfrac{64}{60}\) + \(\dfrac{30}{60}\)
= \(\dfrac{47}{30}\)
\(\dfrac{2}{6}+\dfrac{3}{12}\)
= \(\dfrac{4}{12}\) + \(\dfrac{3}{12}\)
= \(\dfrac{7}{12}\)
\(\dfrac{5}{6}\) + \(\dfrac{1}{3}\)
= \(\dfrac{5}{6}\) + \(\dfrac{2}{6}\)
= \(\dfrac{7}{6}\)
\(\dfrac{1}{3}\) + \(\dfrac{5}{12}\) + \(\dfrac{5}{6}\)
= \(\dfrac{4}{12}\) + \(\dfrac{5}{12}\) + \(\dfrac{10}{12}\)
= \(\dfrac{9}{12}\) + \(\dfrac{10}{12}\)
= \(\dfrac{19}{12}\)
\(\dfrac{5}{8}\) + \(\dfrac{4}{7}\)
= \(\dfrac{35}{56}\) + \(\dfrac{32}{56}\)
= \(\dfrac{67}{56}\)
\(\dfrac{7}{3}\) + \(\dfrac{8}{7}\)
= \(\dfrac{49}{21}\) + \(\dfrac{24}{21}\)
= \(\dfrac{73}{21}\)
\(\dfrac{1}{5}+\dfrac{5}{35}\)
= \(\dfrac{7}{35}\) + \(\dfrac{5}{35}\)
= \(\dfrac{12}{35}\)
b, 3/5 + 4/7 + 2/8 + 10/25 + 9/21 + 28/16
= 3/5 + 4/7 + 2/8 + 2/5 + 3/7 + 14/8
= (3/5 + 2/5) + ( 4/7 + 3/7) + ( 2/8 + 14/8)
= 1 + 1 + 7/4
= 2 + 7/4 = 15/4
c , 8/7 + 7/6 + 5/8 + 10/12 + 24/28 + 6/16
= c , 8/7 + 7/6 + 5/8 + 5/6 + 6/7 + 1/2
= (8/7 + 6/7) + (7/6 + 5/6) + 5/8 + 1/2
= 14/7 + 12/6 + 5/8 + 1/2
= 2 + 2 + 5/8 + 1/2
= 4 + 9/8 = 41/8
2/3 + 7/1 = 2/3 + 7 = 2/3 + 21/3 = 23/3
25/48 + 11/24 = 25/48 + 22/48 = 47/48
5/7 + 3/8 = 40/56 + 21/56 = 61/56
15/24 + 12/6 = 5/8 + 2 = 5/8 + 16/8 = 21/8
5/6 + 4/3 = 5/6 + 8/6 = 13/6
3/8 + 7/12 = 9/24 + 14/24 = 23/24
12/20=6/10=3/5
24/36=8/12=
3/4=9/12=12/16=15/20
2/5=4/10
12/30=4/10
72/45=8/5
1/4=7/28
a) 1/2x(3/4+2/5)
1/2x23/20
23/40
b) 3/4:(8/9+16/3)
3/4:56/9
27/224
c) 1/5:1/10-1/3
2-1/3
5/3
d) 3/4x(20/9-8/15)
3/4x76/45
19/15
e) 1/7:5/14-3/2
=2/5-3/2
-11/10 ( Chị nghĩ lớp 4 chưa học đến số âm nên em xem lại đề nhé)
g) 3/2x(11/6-5/12)
3/2x17/12
17/8
a)\(\frac{1}{2}x\left(\frac{3}{4}+\frac{2}{5}\right)\)
\(=\frac{1}{2}x\left(\frac{15}{20}+\frac{8}{20}\right)\)
\(=\frac{1}{2}x\frac{23}{20}\)
\(=\frac{23}{40}\)
b)\(\frac{3}{4}:\left(\frac{8}{9}+\frac{16}{3}\right)\)
\(=\frac{3}{4}:\left(\frac{8}{9}+\frac{48}{9}\right)\)
\(=\frac{3}{4}:\frac{56}{9}\)
\(=\frac{3}{4}x\frac{9}{56}\)
\(=\frac{27}{224}\)
c) \(\frac{1}{5}:\frac{1}{10}-\frac{1}{3}\)
\(=\frac{1}{5}x10-\frac{1}{3}\)
\(=2-\frac{1}{3}\)
\(=\frac{6}{3}-\frac{1}{3}=\frac{5}{3}\)
d) \(\frac{3}{4}x\left(\frac{20}{9}-\frac{8}{15}\right)\)
\(=\frac{3}{4}x\left(\frac{100}{45}-\frac{24}{45}\right)\)
\(=\frac{3}{4}x\frac{76}{45}\)
\(=\frac{19}{5}\)
e) \(\frac{1}{7}:\frac{5}{14}-\frac{3}{2}\)
\(=\frac{1}{7}x\frac{14}{5}-\frac{3}{2}\)
\(=\frac{2}{5}-\frac{3}{2}\)
\(=\frac{4}{10}-\frac{15}{10}\)
\(=\frac{-11}{10}\)
g) \(\frac{3}{2}x\left(\frac{11}{6}-\frac{5}{12}\right)\)
\(=\frac{3}{2}x\left(\frac{22}{12}-\frac{5}{12}\right)\)
\(=\frac{3}{2}x\frac{17}{12}\)
=\(=\frac{17}{8}\)
\(\frac{2}{7}+\frac{7}{12}=\frac{24}{84}+\frac{49}{84}=\frac{73}{84}\)
\(\frac{25}{48}+\frac{22}{48}=\frac{47}{48}\)
\(\frac{5}{7}+\frac{3}{8}=\frac{40}{56}+\frac{21}{56}=\frac{61}{56}\)
\(\frac{15}{24}+\frac{15}{16}=15.\left(\frac{1}{24}+\frac{1}{16}\right)=\frac{25}{16}\)
\(\frac{5}{6}+\frac{3}{4}=\frac{20+18}{24}=\frac{19}{12}\)
\(\frac{9}{24}+\frac{14}{24}=\frac{23}{24}\)
học tót tích mình hem
\(\dfrac{2}{5}+\dfrac{1}{3}=\dfrac{6+5}{15}=\dfrac{11}{15}\)
\(\dfrac{16}{24}+\dfrac{1}{3}=\dfrac{2}{3}+\dfrac{1}{3}=1\)
\(\dfrac{7}{12}+\dfrac{4}{6}+\dfrac{3}{8}=\dfrac{14}{24}+\dfrac{16}{24}+\dfrac{9}{24}=\dfrac{39}{24}=\dfrac{13}{8}\)
\(1+\dfrac{1}{12}=\dfrac{12+1}{12}=\dfrac{13}{12}\)
2/5+1/3= 6/15+5/15=11/15