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b)1/2*2/3*3/4*4/5*5/6*6/7*7/8*8/9*9/10
=1x2x3x4x5x6x7x8x9
2x3x4x5x6x7x8x9x10
= 1
10
1. 13 / 8 ; 41 / 18 ; 11 / 3 ; 5 / 2 ; 14 / 9 ; 3 .
2. 16 / 15 ; 3 / 2 ; 25 / 24 ; 27 / 8 ; 67 / 40 .
1.
a, Ta có 28=14⇒14+56=1312(Bn tự quy đồng lên nhé !)
b,Ta có1216=34⇒18+34=78(Bn tự quy đồng lên nhé !)
c,Ta có636=16⇒14+16=512(Bn tự quy đồng lên nhé !)
d,Ta có1218=23⇒23+14=1112(Bn tự quy đồng lên nhé !)
7.Phần này mk chỉ cho đáp án thuia.67 ;
b,420=15 ;
c,615 ;
d,129
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
a) \(\frac{2}{9}+\frac{5}{6}\times\frac{4}{7}\)
\(=\frac{2}{9}+\frac{10}{21}\)
\(=\frac{44}{63}\)
b) \(\frac{21}{25}+\frac{4}{5}:\frac{8}{6}\)
\(=\frac{21}{25}+\frac{3}{5}\)
\(=\frac{36}{25}\)
c) \(\frac{17}{24}-\frac{1}{3}+\frac{3}{4}\)
\(=\frac{3}{8}+\frac{3}{4}\)
\(=\frac{9}{8}\)
a) \(\frac{2}{9}+\frac{5}{6}\times\frac{4}{7}=\frac{2}{9}+\frac{10}{21}=\frac{14}{63}+\frac{30}{63}=\frac{44}{63}\)
b) \(\frac{21}{25}+\frac{4}{5}\div\frac{8}{6}=\frac{21}{25}+\frac{4}{5}\times\frac{6}{8}=\frac{21}{25}+\frac{3}{5}=\frac{21}{25}+\frac{15}{25}=\frac{36}{25}\)
c) \(\frac{17}{24}-\frac{1}{3}+\frac{3}{4}=\frac{17}{24}-\frac{8}{24}+\frac{18}{24}=\frac{27}{24}=\frac{9}{8}\)
a) 1/2 = 2/4 = 3/6 = 4/8 = 5/10
b) 1/3 = 2/6 = 3/9 = 4/12 = 5/15
c) 3/4 = 6/8 = 9/12 = 12/16 = 18/24
d) 4/3 = 8/6 = 12/9 = 16/12 = 20/15
e) 6/4 = 3/2 ; 6/3 = 4/2
g) 4/2 12/6 = 24/12
\(\dfrac{1}{3}+\dfrac{3}{4}+\dfrac{1}{2}=\dfrac{4}{12}+\dfrac{9}{12}+\dfrac{6}{12}=\dfrac{19}{12}\)
\(\dfrac{6}{8}+\dfrac{2}{4}+\dfrac{6}{24}=\dfrac{3}{4}+\dfrac{2}{4}+\dfrac{1}{4}=\dfrac{6}{4}=\dfrac{3}{2}\)
\(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{5}{6}=\dfrac{3}{6}+\dfrac{2}{6}+\dfrac{5}{6}=\dfrac{10}{6}=\dfrac{5}{3}\)
\(\dfrac{3}{5}+\dfrac{3}{2}+2=\dfrac{6}{10}+\dfrac{15}{10}+\dfrac{20}{10}=\dfrac{41}{10}\)
\(\dfrac{1}{3}+\dfrac{3}{4}+\dfrac{1}{2}=\dfrac{13}{12}+\dfrac{1}{2}=\dfrac{19}{12}\\ \dfrac{6}{8}+\dfrac{2}{4}+\dfrac{6}{24}=\dfrac{5}{4}+\dfrac{6}{24}=\dfrac{3}{2}\\ \dfrac{1}{2}+\dfrac{1}{3}+\dfrac{5}{6}=\dfrac{5}{6}+\dfrac{5}{6}=\dfrac{10}{6}\\ \dfrac{3}{5}+\dfrac{3}{2}+2=\dfrac{21}{10}+\dfrac{20}{10}=\dfrac{41}{10}\)