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`a, 4/9 + 2/5 + 5/9= (4/9 +5/9) + 2/5= 1 + 2/5= 5/5 + 2/5= 7/5`
`b, 6/13 + 5/8 + 7/13=(6/13 + 7/13) + 5/8=1+5/8= 8/8 + 5/8= 13/8`
`c, 5/11 + 6/25 + 66/121 = ( 5/11 + 66/121 ) + 6/25=1 + 6/25 = 25/25 + 6/25 = 31/25`
`d, 1/2 + 1/3 + 1/4 + 1/6 + 1/12 + 1/24= (1/2 + 1/4) +(1/3 + 1/6) + (1/12 + 1/24)= 3/4 + 1/2 + 1/8= 6/8 + 4/8 + 1/8= 11/8`
`@ yl`
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A) \(\frac{7}{8}-\frac{5}{12}=\frac{84}{96}-\frac{40}{96}=\frac{44}{96}=\frac{11}{24}\)
B)\(\frac{8}{15}-\frac{2}{5}=\frac{8}{15}-\frac{6}{15}=\frac{2}{15}\)
C)\(\frac{5}{6}-\frac{3}{10}=\frac{50}{60}-\frac{18}{60}=\frac{32}{60}=\frac{8}{15}\)
D)\(\frac{7}{10}-\frac{1}{5}=\frac{7}{10}-\frac{2}{10}=\frac{5}{10}=\frac{1}{2}\)
2)A)\(\frac{5}{10}-\frac{2}{15}=\frac{1}{2}-\frac{2}{15}=\frac{15}{30}-\frac{4}{30}=\frac{11}{30}\)
B)\(\frac{5}{20}-\frac{1}{6}=\frac{1}{4}-\frac{1}{6}=\frac{6}{24}-\frac{4}{24}=\frac{2}{24}=\frac{1}{12}\)
C)\(\frac{6}{18}-\frac{6}{24}=\frac{1}{3}-\frac{1}{4}=\frac{4}{12}-\frac{3}{12}=\frac{1}{12}\)
D)\(\frac{5}{9}-\frac{3}{12}=\frac{5}{9}-\frac{1}{4}=\frac{20}{36}-\frac{9}{36}=\frac{11}{36}\)
Chúc bạn học tốt
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\(a)9+\frac{24}{25}=\frac{9\cdot25+24}{25}=\frac{249}{25}\)
\(b)\frac{1}{20}+\frac{1}{4}+\frac{2}{5}=\frac{1}{20}+\frac{5}{20}+\frac{8}{20}=\frac{1+5+8}{20}=\frac{14}{20}=\frac{7}{10}\)
\(c)\frac{7}{12}+4=\frac{7}{12}+\frac{4}{1}=\frac{7+48}{12}=\frac{55}{12}\)
\(d)10+\frac{9}{8}=\frac{10}{1}+\frac{9}{8}=\frac{80+9}{8}=\frac{89}{8}\)
\(e)\frac{1}{4}+\frac{2}{25}+\frac{9}{100}=\frac{25}{100}+\frac{8}{100}+\frac{9}{100}=\frac{25+8+9}{100}=\frac{42}{100}=\frac{21}{50}\)
Còn 3 câu làm tương tự
Ba câu còn lại mình làm luôn :D
\(f)\frac{28}{90}+6=\frac{14}{45}+6=\frac{14}{45}+\frac{6}{1}=\frac{14+270}{45}=\frac{284}{45}\)
\(g)\frac{3}{7}+\frac{4}{9}+\frac{4}{7}+\frac{7}{11}=(\frac{3}{7}+\frac{4}{7})+\frac{4}{9}+\frac{4}{11}=1+\frac{4}{9}+\frac{4}{11}\)
\(=\frac{7}{7}+\frac{4}{9}+\frac{4}{11}=\frac{693+308+252}{693}=\frac{1253}{693}=\frac{179}{99}\)
\(h)\frac{1}{8}+\frac{1}{12}+\frac{3}{8}+\frac{5}{12}=(\frac{1}{8}+\frac{3}{8})+(\frac{1}{12}+\frac{5}{12})=\frac{4}{8}+\frac{6}{12}=\frac{1}{2}+\frac{1}{2}=1\)
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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
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\(\frac{7}{9}+\frac{6}{7}\times\frac{4}{5}=\frac{7}{9}+\frac{24}{35}=\frac{361}{315}\)
\(\frac{21}{23}+\frac{4}{5}:\frac{6}{8}=\frac{21}{23}+\frac{16}{15}=\frac{548}{345}\)
\(\frac{5}{8}\times\frac{4}{9}:\frac{2}{3}=\frac{5}{18}:\frac{2}{3}=\frac{5}{12}\)
\(\frac{7}{12}+\frac{5}{6}-\frac{21}{24}=\frac{14}{24}+\frac{20}{24}-\frac{21}{24}=\frac{11}{24}\)
b,
\(\frac{21}{23}+\frac{4}{5}:\frac{6}{8}=\frac{21}{23}+\frac{4}{5}.\frac{8}{6}=\frac{21}{23}+\frac{16}{15}=1\frac{338}{345}\)
c,
\(\frac{5}{8}.\frac{4}{9}.\frac{3}{2}=\frac{5}{12}\)
d,
\(\frac{7}{12}+\frac{5}{6}-\frac{21}{24}=\frac{14}{24}+\frac{20}{24}-\frac{21}{24}=\frac{13}{24}\)
chán thật
a)7/18 b)23/24
a) 7/18
b) 3/8