bài 4: cho các PS sau: 8/10;27/63;28/35;36/84;32/40;15/35 a) các PS bằng PS 4/5 là:_______________ b) các PS bằng PS 3/7 là:_______________
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Bài 2:
a: \(\dfrac{1}{4};\dfrac{2}{5}\)
\(\dfrac{1}{4}=\dfrac{1\cdot5}{4\cdot5}=\dfrac{5}{20}\)
\(\dfrac{2}{5}=\dfrac{2\cdot4}{5\cdot4}=\dfrac{8}{20}\)
\(\dfrac{2}{3};\dfrac{7}{8}\)
\(\dfrac{2}{3}=\dfrac{2\cdot8}{3\cdot8}=\dfrac{16}{24}\)
\(\dfrac{7}{8}=\dfrac{7\cdot3}{8\cdot3}=\dfrac{21}{24}\)
\(\dfrac{3}{4};\dfrac{5}{6}\)
\(\dfrac{3}{4}=\dfrac{3\cdot3}{4\cdot3}=\dfrac{9}{12}\)
\(\dfrac{5}{6}=\dfrac{5\cdot2}{6\cdot2}=\dfrac{10}{12}\)
b: \(\dfrac{1}{3};\dfrac{7}{9}\)
\(\dfrac{1}{3}=\dfrac{1\cdot3}{3\cdot3}=\dfrac{3}{9}\)
\(\dfrac{7}{9}=\dfrac{7\cdot1}{9\cdot1}=\dfrac{7}{9}\)
\(\dfrac{3}{4};\dfrac{9}{24}\)
\(\dfrac{3}{4}=\dfrac{3\cdot6}{4\cdot6}=\dfrac{18}{24}\)
\(\dfrac{9}{24}=\dfrac{9\cdot1}{24\cdot1}=\dfrac{9}{24}\)
\(\dfrac{7}{10};\dfrac{19}{30}\)
\(\dfrac{7}{10}=\dfrac{7\cdot3}{10\cdot3}=\dfrac{21}{30}\)
\(\dfrac{19}{30}=\dfrac{19\cdot1}{30\cdot1}=\dfrac{19}{30}\)
Bài 1:
\(\dfrac{36}{108}=\dfrac{36:36}{108:36}=\dfrac{1}{3}\)
\(\dfrac{28}{30}=\dfrac{28:2}{30:2}=\dfrac{14}{15}\)
\(\dfrac{42}{98}=\dfrac{42:14}{98:14}=\dfrac{3}{7}\)
\(\dfrac{15}{120}=\dfrac{15:15}{120:15}=\dfrac{1}{8}\)
\(\dfrac{84}{364}=\dfrac{84:28}{364:28}=\dfrac{3}{13}\)
\(\dfrac{120}{100}=\dfrac{120:20}{100:20}=\dfrac{6}{5}\)
\(\dfrac{418}{38}=\dfrac{418:38}{38:38}=\dfrac{11}{1}=11\)
\(\dfrac{96}{1056}=\dfrac{96:96}{1056:96}=\dfrac{1}{11}\)
\(\dfrac{3838}{4040}=\dfrac{3838:101}{4040:101}=\dfrac{38}{40}=\dfrac{38:2}{40:2}=\dfrac{19}{20}\)
\(\dfrac{119119}{123123}=\dfrac{119119:1001}{123123:1001}=\dfrac{119}{123}\)
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\(\dfrac{3}{25}=\dfrac{3\times4}{25\times4}=\dfrac{12}{100}\\ \dfrac{7}{8}=\dfrac{7\times125}{8\times125}=\dfrac{875}{1000}\\ \dfrac{9}{45}=\dfrac{9:9}{45:9}=\dfrac{1}{5}=\dfrac{1\times2}{5\times2}=\dfrac{2}{10}\)
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Bài 1 :
7/21 , 6/21 , 5/21
Bài 2 :
2/5 = 6/15 = 24/60
4/7 = 8/14 = 16/28
Bài 3 :
1/2 = 5/10
4/5 = 80/100
71/20 = 355/100
84/400 = 21/100
Bài 4 :
2/7 , 3/5 , 7/8 , 4/3
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a. \(\dfrac{7}{3}\)
\(b.\dfrac{5}{8}\)
\(c.\dfrac{5}{5}\)
a) \(\dfrac{9}{1};\dfrac{8}{2};\dfrac{7}{3};\dfrac{6}{4}\)
(Để phân số lớn hơn 1 thì tử số phải lớn hơn mẫu số.)
b) \(\dfrac{1}{9};\dfrac{2}{8};\dfrac{3}{7};\dfrac{4}{6}\)
(Để phân số nhỏ hơn 1 thì mẫu số phải lớn hơn tử số.)
c)\(\dfrac{5}{5}\)
(Để phân số bằng 1 thì tử số bằng mẫu số.)
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a. (36+54)x7+7x9+7
=7x90+7x(9+1)
=7x(90+10)
=7x100
=700
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(7/10+3/10)+3/4+2/7+1/2=10/10+3/4+2/7+1/2=1280/560nhe
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5+a/8+a/2=4-a/5-a ta co (5+8)*2=36/2=18
a=18 vay b se =18/(4+5)=2
do vay =18 b=2
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A} x - 8 / 2x - 17
x=8
B} x - 4 / x - 1
x=4
câu C mk không tính ra, mk chỉ giúp được 2 câu trên thôi
a.
các phân số bằng \(\dfrac{4}{5}\) là: \(\dfrac{8}{10};\dfrac{28}{25};\dfrac{32}{40}\)
b.
Các phân số bằng \(\dfrac{3}{7}\) là: \(\dfrac{27}{63};\dfrac{36}{84};\dfrac{15}{35}\)
nghi nhầm r! 28/35