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a: \(\dfrac{-7}{15}=\dfrac{-7\cdot4}{15\cdot4}=\dfrac{-28}{60}\)
\(\dfrac{5}{12}=\dfrac{5\cdot5}{12\cdot5}=\dfrac{25}{60}\)
b: \(\dfrac{1}{5}=\dfrac{1\cdot6}{5\cdot6}=\dfrac{6}{30}\)
\(\dfrac{-2}{3}=\dfrac{-2\cdot10}{3\cdot10}=\dfrac{-20}{30}\)
\(\dfrac{7}{10}=\dfrac{7\cdot3}{10\cdot3}=\dfrac{21}{30}\)
c: \(\dfrac{-15}{50}=\dfrac{-15\cdot3}{50\cdot3}=\dfrac{-45}{150}\)
\(\dfrac{9}{10}=\dfrac{9\cdot15}{10\cdot15}=\dfrac{135}{150}\)
\(\dfrac{26}{-30}=\dfrac{-26}{30}=\dfrac{-26\cdot5}{30\cdot5}=\dfrac{-130}{150}\)
d: \(\dfrac{7}{10}=\dfrac{7\cdot51}{10\cdot51}=\dfrac{357}{510}\)
\(\dfrac{-5}{-15}=\dfrac{1}{3}=\dfrac{1\cdot170}{3\cdot170}=\dfrac{170}{510}\)
\(\dfrac{3}{17}=\dfrac{3\cdot30}{17\cdot30}=\dfrac{90}{510}\)
e: \(\dfrac{-4}{-75}=\dfrac{4}{75}=\dfrac{4}{75}\)
\(\dfrac{-3}{5}=\dfrac{-3\cdot15}{5\cdot15}=\dfrac{-45}{75}\)
\(\dfrac{8}{25}=\dfrac{8\cdot3}{25\cdot3}=\dfrac{24}{75}\)
f: \(-\dfrac{4}{5}=\dfrac{-4\cdot7}{5\cdot7}=\dfrac{-28}{35}\)
\(\dfrac{6}{7}=\dfrac{6\cdot5}{7\cdot5}=\dfrac{30}{35}\)
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Bài 1:
\(\dfrac{-5}{18}=\dfrac{-20}{72};\dfrac{7}{-24}=\dfrac{-21}{72}.\)
\(\dfrac{-15}{-40}=\dfrac{3}{8}=\dfrac{9}{24};\dfrac{24}{-72}=\dfrac{-1}{3}=\dfrac{-8}{24}.\)
Bài 3:
a) \(\dfrac{2}{3}h=\dfrac{8}{12}h;\dfrac{3}{4}h=\dfrac{9}{12}h.\Rightarrow\dfrac{2}{3}h< \dfrac{3}{4}h.\)
b) \(\dfrac{4}{5}km/h=\dfrac{8}{10}km/h;\dfrac{9}{10}km/h.\Rightarrow\dfrac{4}{5}km/h< \dfrac{9}{10}km/h.\)
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\(a,MSC:170\\ \dfrac{7}{10}=\dfrac{7.17}{17.10}=\dfrac{119}{170}\\ \dfrac{-5}{15}=-\dfrac{1}{5}=\dfrac{1.34}{5.34}=\dfrac{34}{170}\\ \dfrac{3}{17}=\dfrac{3.10}{17.10}=\dfrac{30}{17}\\ b,MSC:525\\ \dfrac{-4}{-75}=\dfrac{4}{75}=\dfrac{4.7}{75.7}=\dfrac{28}{525}\\ \dfrac{-3}{5}=\dfrac{-3.105}{5.105}=\dfrac{-315}{525}\\ \dfrac{8}{35}=\dfrac{8.15}{35.15}=\dfrac{120}{525}\)
Câu 1:
MSC=60
7/10=7.6/10.6=42/60 5/-12=-5/12=-5.5/12.5=-25/60
Câu 2:
17/34=1/2; -12/22=-6/11; -25/35=-5/7; 125/75=5/3
Câu 3:
MSC=24
1/3=1.8/3.8=8/24 -3/8=-3.3/8.3=-9/24 17/24=17/24
Bài 2:
a: 2/5=14/35
3/7=15/35
b: -3/4=-9/12
-7/-12=7/12
c: 5/9=60/108
-11/-12=11/12=99/108
d: -4/7=-36/63
8/9=56/63
-10/21=-30/63
Bài 2:
a: 2/5=14/35
3/7=15/35
b: -3/4=-9/12
-7/-12=7/12
c: 5/9=60/108
-11/-12=11/12=99/108
d: -4/7=-36/63
8/9=56/63
-10/21=-30/63
Tk mình đi mọi người mình bị âm nè!
Ai tk mình mình tk lại cho
Bài 1 :
a) 40/49 > 15/21
b) 22/49 > 3/8
c) 25/46 < 12/18
Bài 1:
\(a.\) \(\dfrac{5}{12}\) và \(\dfrac{-4}{9}\)
Mẫu số chung của 2 phân số: \(36.\)
Ta có:
\(\dfrac{5}{12}=\dfrac{5\cdot3}{12\cdot3}=\dfrac{15}{36};\dfrac{-4}{9}=\dfrac{-4\cdot4}{9\cdot4}=\dfrac{-16}{36}\)
\(b.\) \(\dfrac{-7}{15}\) và \(\dfrac{5}{12}\)
Mẫu số chung của hai phân số: \(60.\)
Ta có:
\(\dfrac{-7}{15}=\dfrac{-7\cdot4}{15\cdot4}=\dfrac{-28}{60};\dfrac{5}{12}=\dfrac{5\cdot5}{12\cdot5}=\dfrac{25}{60}\)
\(c.\)\(\dfrac{1}{5};\dfrac{-2}{3}\) và \(\dfrac{7}{10}\)
Mẫu số chung của 3 phân số: \(30.\)
Ta có:
\(\dfrac{1}{5}=\dfrac{1\cdot6}{5\cdot6}=\dfrac{6}{30};\dfrac{-2}{3}=\dfrac{-2\cdot10}{3\cdot10}=\dfrac{-20}{30};\dfrac{7}{10}=\dfrac{7\cdot3}{10\cdot3}=\dfrac{21}{30}\)
Bài 1:
a)
Mẫu số chung 2 phân số: 36
\(\dfrac{5}{12}=\dfrac{5\cdot3}{12\cdot3}=\dfrac{15}{36}\)
\(\dfrac{-4}{9}=\dfrac{-4\cdot4}{9\cdot4}=\dfrac{-16}{36}\)
b)
Mẫu số chung 2 phân số: 60
\(\dfrac{-7}{15}=\dfrac{-7\cdot4}{15\cdot4}=\dfrac{-28}{60}\)
\(\dfrac{5}{12}=\dfrac{5\cdot5}{12\cdot5}=\dfrac{25}{60}\)
c) Mẫu số chung 3 phân số: \(75\)
\(\dfrac{-4}{-75}=\dfrac{-4\cdot\left(-1\right)}{-75\cdot\left(-1\right)}=\dfrac{4}{75}\)
\(\dfrac{-3}{5}=\dfrac{-3\cdot15}{5\cdot15}=-\dfrac{45}{75}\)
\(\dfrac{8}{25}=\dfrac{8\cdot3}{25\cdot3}=\dfrac{24}{75}\)
Bài 2:
a) Rút gọn:
\(\dfrac{-15}{50}=\dfrac{-15:5}{50:5}=\dfrac{-3}{10}\)
\(\dfrac{9}{10}=\dfrac{9:1}{10:1}=\dfrac{9}{10}\)
\(\dfrac{26}{-30}=\dfrac{26:-2}{-30:-2}=\dfrac{-13}{15}\)
Mẫu số chung 3 phân số: 30
\(\dfrac{-3}{10}=\dfrac{-3\cdot3}{10\cdot3}=\dfrac{-9}{30}\)
\(\dfrac{9}{10}=\dfrac{9\cdot3}{10\cdot3}=\dfrac{27}{30}\)
\(\dfrac{-13}{15}=\dfrac{-13\cdot2}{15\cdot2}=\dfrac{-26}{30}\)
b)
Rút gọn:
\(\dfrac{-5}{-15}=\dfrac{-5:\left(-5\right)}{-15:\left(-5\right)}=\dfrac{1}{3}\)
Mẫu số chung 3 Phân số: 510
\(\dfrac{7}{10}=\dfrac{357}{510};\dfrac{1}{3}=\dfrac{170}{510};\dfrac{3}{17}=\dfrac{90}{510}\)
c) Mẫu số chung 3 phân số: 75
\(\dfrac{-4}{-75}=\dfrac{4}{75};\dfrac{-3}{5}=-\dfrac{45}{75};\dfrac{8}{25}=\dfrac{24}{75}\)
Bài 3:
a) rút gọn:
\(\dfrac{42}{63}=\dfrac{42:21}{63:21}=\dfrac{2}{3}\)
\(\dfrac{60}{72}=\dfrac{60:12}{72:12}=\dfrac{5}{6}\)
Mẫu số chung 2 phân số: 6
\(\dfrac{2}{3}=\dfrac{2\cdot2}{3\cdot2}=\dfrac{4}{6}\)
Vì \(4< 5\) nên\(\dfrac{4}{6}< \dfrac{5}{6}\)
Vậy \(\dfrac{42}{63}< \dfrac{60}{72}\)
b) rút gọn:
\(\dfrac{34}{-119}=\dfrac{34:-17}{-119:-17}=\dfrac{-2}{7}\)
\(\dfrac{-93}{248}=\dfrac{-93:31}{248:31}=\dfrac{-3}{8}\)
Ta có:
Mẫu số chung 2 phân số: 56
\(\dfrac{-2}{7}=\dfrac{-2\cdot8}{7\cdot8}=\dfrac{-16}{56}\)
\(\dfrac{-3}{8}=\dfrac{-3\cdot7}{8\cdot7}=\dfrac{-21}{56}\)
Vì \(-16>-21\) nên\(\dfrac{-16}{56}>\dfrac{-21}{56}\)
Vậy \(\dfrac{34}{-119}>\dfrac{-93}{248}\)