Quy đồng các PS: 8/3;-4/5;5/7
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21 tháng 1
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:
\(\dfrac{36}{108}=\dfrac{36:36}{108:36}=\dfrac{1}{3}\)
\(\dfrac{28}{30}=\dfrac{28:2}{30:2}=\dfrac{14}{15}\)
\(\dfrac{42}{98}=\dfrac{42:14}{98:14}=\dfrac{3}{7}\)
\(\dfrac{15}{120}=\dfrac{15:15}{120:15}=\dfrac{1}{8}\)
\(\dfrac{84}{364}=\dfrac{84:28}{364:28}=\dfrac{3}{13}\)
\(\dfrac{120}{100}=\dfrac{120:20}{100:20}=\dfrac{6}{5}\)
\(\dfrac{418}{38}=\dfrac{418:38}{38:38}=\dfrac{11}{1}=11\)
\(\dfrac{96}{1056}=\dfrac{96:96}{1056:96}=\dfrac{1}{11}\)
\(\dfrac{3838}{4040}=\dfrac{3838:101}{4040:101}=\dfrac{38}{40}=\dfrac{38:2}{40:2}=\dfrac{19}{20}\)
\(\dfrac{119119}{123123}=\dfrac{119119:1001}{123123:1001}=\dfrac{119}{123}\)
ND
Nguyễn Đức Trí
VIP
6 tháng 8 2023
a) \(\dfrac{8}{9}< 1;\dfrac{13}{7}>1\Rightarrow\dfrac{8}{9}< \dfrac{13}{7}\)
b) \(\dfrac{16}{27}>\dfrac{15}{27}>\dfrac{15}{29}\Rightarrow\dfrac{16}{27}>\dfrac{15}{29}\)
13 tháng 9 2017
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
NV
Nguyễn Việt Lâm
Giáo viên
18 tháng 1
1C sai \(\dfrac{9}{27}=\dfrac{1}{3}\) mới đúng
2. Em ghi thiếu 2 phân số cần quy đồng
3.C
4.D
Ta có \(\frac{8}{3}=\frac{280}{105}\)
\(\frac{-4}{5}=\frac{-84}{105}\)
\(\frac{5}{7}=\frac{75}{105}\)
\(\frac{8}{3}=\frac{8.35}{3.35}=\frac{280}{105}\)
\(\frac{-4}{5}=\frac{-4.21}{5.21}=\frac{-84}{105}\)
\(\frac{5}{7}=\frac{5.15}{7.15}=\frac{75}{105}\)