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\(\frac{4}{3}\times\frac{9}{8}\times...\times\frac{81}{80}=\frac{2^2}{1\times3}\times\frac{3^2}{2\times4}\times...\times\frac{9^2}{8\times10}\)
\(=\frac{2\times3\times4\times...\times9}{1\times2\times3\times...\times8}\times\frac{2\times3\times4\times...\times9}{3\times4\times5\times...\times10}\\ =\frac{9}{1}\times\frac{2}{10}=\frac{9}{5}\)
4/3.9/8.16/15.25/24.36/35.49/48.64/63.81/80
=3/2.16/15.25/24.36/35.49/48.64/63.81/80
=5/3.36/35.49/48.64/63.81/80
=7/4.64/63.81/80
=9/5
+
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a,\(\frac{4}{3}\)x \(\frac{9}{8}\)x \(\frac{16}{15}\)x \(\frac{25}{24}\)
= \(\frac{5}{3}\)
b, \(\frac{4}{3}\)x \(\frac{9}{8}\)x \(\frac{16}{15}\)x \(\frac{25}{24}\)x \(\frac{36}{35}\)x \(\frac{49}{48}\)x \(\frac{64}{63}\)x \(\frac{81}{80}\)
= \(\frac{9}{5}\)
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Bài 1:
a: 6/9=2/3
6/24=1/4
48/96=1/2
42/98=3/7
b: 24/36=2/3
18/30=3/5
15/120=1/8
80/240=1/3
c: 5/25=1/5
75/100=3/4
64/720=4/45
16/1000=2/125
Bài 2:
Các phân số bằng 2/3 là 34/51; 20/30; 84/126
Bài 1 :
a) 6/9 = 2/3 ; 6/24 = 1/4 ; 48/96 = 1/2 ; 42/98 = 3/7
b) 24/36 = 2/3 ; 18/30 = 3/5 ; 15/120 = 1/8 ; 80 / 240 = 1/3
c) 5 / 25 = 1/5 ; 75/100=3/4 ; 64/720=4/45 ; 16/1000=2/125
Bài 2 :
Các phân số bằng 2/3 là :
\(\text{34/51; 20/30; 84/126}\)
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1/10 + 4/20 + 9/30 + 16/40 + 25/50 + 36/60 + 49/70 + 64/80 + 81/90
= 1/10 + 2/10 + 3/10 + 4/10 + 5/10 + 6/10 + 7/10 + 8/10 + 9/10
=(1+2+3+....+9) /10
=(1+9)x9:2 /10
=45/10=4,5
chắc chắn đúng đó
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{1}{10}+\dfrac{4}{20}+\dfrac{9}{30}+\dfrac{16}{40}+\dfrac{25}{50}+\dfrac{36}{60}+\dfrac{49}{70}+\dfrac{64}{80}+\dfrac{81}{90}\)
\(=\dfrac{1}{10}+\dfrac{1}{5}+\dfrac{3}{10}+\dfrac{2}{5}+\dfrac{1}{2}+\dfrac{3}{5}+\dfrac{7}{10}+\dfrac{4}{5}+\dfrac{9}{10}\)
\(=\left(\dfrac{1}{10}+\dfrac{3}{10}+\dfrac{7}{10}+\dfrac{9}{10}\right)+\left(\dfrac{1}{5}+\dfrac{2}{5}+\dfrac{3}{5}+\dfrac{4}{5}\right)+\dfrac{1}{2}\)
\(=2+2+\dfrac{1}{2}\)
\(=4+\dfrac{1}{2}\)
\(=\dfrac{8}{2}+\dfrac{1}{2}=\dfrac{9}{2}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\dfrac{16}{24};\dfrac{14}{15};\dfrac{25}{27};\dfrac{50}{100}\)
b) \(\dfrac{9}{4};\dfrac{5}{4};\dfrac{7}{5};\dfrac{19}{7};\dfrac{49}{36}\)
c) \(\dfrac{13}{13};\dfrac{35}{35}\)
a: 16/24; 14/15; 25/27; 50/100
b: 9/4; 5/4; 7/5; 19/7; 49/36
c: 13/13; 35/35
=(1-1/2)(1+1/2)*...*(1+1/10)(1-1/10)
=1/2*2/3*...*9/10*3/2*4/3*...*11/10
=1/10*11/2
=11/20