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\(\dfrac{9}{12}=\dfrac{45}{60}\)
\(\dfrac{7}{15}=\dfrac{28}{60}\)
\(\dfrac{9}{12}=\dfrac{45}{60}\)
\(\dfrac{7}{15}=\dfrac{28}{60}\)
?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
\(a) {4\over12}={4.5\over12.5}={20\over60}\)
\({1\over5}={1.12\over5.12}={12\over60}\)
\({-4\over15}={-4.4\over15.5}={-16\over60}\)
b)\({-7\over10}={-7.3\over10.3}={-21\over20}\)
\({1\over2}={1.15\over2.15}={15\over30}\)
\({-4\over15}={-4.2\over15.2}={-8\over30}\)
c)\({-5\over14}={-5.30\over14.30}={-150\over420}\)
\({3\over20}={3.21\over20.21}={63\over420}\)
\({-4\over21}={-4.20\over21.20}={-80\over420}\)
d)\({4\over18}={4.5\over18.5}={20\over90}\)
\({1\over18}={1.18\over5.18}={18\over90}\)
\({-6\over15}={-6.6\over15.6}={-36\over90}\)
Nói lời giữ lời nha ^_^..........Mệt wá........
a)4/12=1.5/12.5=5/60
1/5=1.12/5.12=5/60
-4/15=-4.4/15.4=-16/60
b)-7/10=-7.3/10.3=-21/30
1/2=1.15/2.15=15/30
-4/15=-4.2/15.2=-8/30
c)-5/14=-5.30/14/30=150/420
3/20=3.21/20.21=63/420
-4/21=-4.20/21.20=-80/420
d)4/18=4.5/18.5=20/90
1/5=1.18/5.18=18/90
-6/15=-6.6/15.6=-36/90
Tìm x:
\(\frac{x}{10}=\frac{3}{5}\)
Ta có:
x . 5 = 10 . 3
x . 5 = 30
x = 30 : 5
x = 6
Vậy x = 6
Bài 2: Quy đồng mẫu số:
\(\frac{7}{10};-\frac{3}{4};2\)
MSC : 20
\(\frac{7}{10}=\frac{7.2}{10.2}=\frac{14}{20}\)
\(\frac{3}{4}=\frac{3.5}{4.5}=\frac{15}{20}\)
\(2=\frac{2}{1}=\frac{2.20}{1.20}=\frac{40}{20}\)
Vậy quy đồng mẫu số của \(\frac{7}{10};-\frac{3}{4};2\) ta được \(\frac{14}{20};\frac{15}{20};\frac{40}{20}\)
HT
1: Rút gọn
a) \(-\dfrac{33}{51}=\dfrac{-33:3}{51:3}=\dfrac{-11}{17}\)
b) \(\dfrac{156}{-168}=\dfrac{-156}{168}=\dfrac{-156:12}{168:12}=\dfrac{-13}{14}\)
c) \(\dfrac{-75}{-100}=\dfrac{75}{100}=\dfrac{75:25}{100:25}=\dfrac{3}{4}\)
2: Quy đồng mẫu:
a) \(-\dfrac{3}{8}\) và \(\dfrac{5}{4}\)
MSC: 8
\(-\dfrac{3}{8}=\dfrac{-3}{8}\)
\(\dfrac{5}{4}=\dfrac{5\cdot2}{4\cdot2}=\dfrac{10}{8}\)
b) \(\dfrac{-7}{6}\) ; \(\dfrac{5}{12}\) và \(-\dfrac{5}{6}\)
MSC: 12
\(-\dfrac{7}{6}=\dfrac{-7\cdot2}{6\cdot2}=\dfrac{-14}{12}\)
\(\dfrac{5}{12}=\dfrac{5}{12}\)
\(\dfrac{-5}{6}=\dfrac{-5\cdot2}{6\cdot2}=\dfrac{-10}{12}\)
\(\dfrac{9}{12}=\dfrac{135}{180}\)
\(\dfrac{7}{15}=\dfrac{84}{180}\)