rút gọn rồi so sánh 2 phân số
a) 18/27 và 24/56 ......................
b) 36/90 và 50/125 ....................
c 121/77 và 88/64 .......................
d) 52/91 và 60/84 .........................
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ta có : 52/91=4/7
60/84=5/7
Vì mẫu 2 phân số trên bằng nhau, 4<5 nên 4/7<5/7
hay 52/91<60/84
Vậy ....
a)36/48>12/48
=>6/8>3/12
b)135/225<180/225
=>15/25<36/45
c)1575/2835>1323/2835
=>15/27>49/105
Chúc e học tốt
Bạn ơi bạn có thể trình bày cái phần rút gọn được ko
a. 18/72 = 1/4
15/20 = 3/4
vì 1/4<3/4 nên 18/72<15/20
b. 24/36 = 2/3
20/50 = 2/5
2/3>2/5 nên 24/36>20/50
a, \(\dfrac{18}{72}\) = \(\dfrac{18:18}{72:18}\) = \(\dfrac{1}{4}\); \(\dfrac{15}{20}\) = \(\dfrac{3}{4}\)
Vì \(\dfrac{1}{4}\) < \(\dfrac{3}{4}\) nên \(\dfrac{18}{72}\) < \(\dfrac{15}{20}\)
b, \(\dfrac{24}{36}\) = \(\dfrac{24:12}{36:12}\) = \(\dfrac{2}{3}\); \(\dfrac{20}{50}\) = \(\dfrac{20:10}{50:10}\) = \(\dfrac{2}{5}\)
Vì \(\dfrac{2}{3}\) > \(\dfrac{2}{5}\) nên \(\dfrac{24}{36}\) > \(\dfrac{20}{50}\)
a: 3/8=36/96
5/12=40/96
b: -2/9=-24/108
-5/12=-45/108
c: -3/16=-63/336
-5/24=-70/336
-21/56=-126/336
Câu 3:
a) \(\dfrac{12}{36}=\dfrac{12:12}{36:12}=\dfrac{1}{3}\)
\(\dfrac{-16}{20}=\dfrac{-16:4}{20:4}=\dfrac{-4}{5}\)
b) \(\dfrac{21}{105}=\dfrac{21:21}{105:21}=\dfrac{1}{5}\)
\(\dfrac{35}{150}=\dfrac{35:5}{150:5}=\dfrac{7}{30}\)
Câu 4:
a) \(\dfrac{3}{10}+\dfrac{5}{10}=\dfrac{3+5}{10}=\dfrac{8}{10}=\dfrac{4}{5}\)
b) Ta có: \(\left(-27\right)\cdot36+64\cdot\left(-27\right)+23\cdot\left(-100\right)\)
\(=\left(-27\right)\cdot\left(64+36\right)+23\cdot\left(-100\right)\)
\(=-27\cdot100-23\cdot100\)
\(=100\left(-27-23\right)\)
\(=-50\cdot100=-5000\)
c) \(\dfrac{5}{8}+\dfrac{3}{12}=\dfrac{15}{24}+\dfrac{6}{24}=\dfrac{21}{24}=\dfrac{7}{8}\)
d) Ta có: \(\dfrac{-2}{17}+\dfrac{3}{19}+\dfrac{-15}{17}+\dfrac{16}{19}+\dfrac{5}{6}\)
\(=\left(-\dfrac{2}{17}+\dfrac{-15}{17}\right)+\left(\dfrac{3}{19}+\dfrac{16}{19}\right)+\dfrac{5}{6}\)
\(=-1+1+\dfrac{5}{6}\)
\(=\dfrac{5}{6}\)
\(a,\dfrac{52}{32}=\dfrac{13}{8}\\ \dfrac{55}{65}=\dfrac{11}{13}\\ MSC:104\\ =>\dfrac{13}{8}=\dfrac{13.13}{8.13}=\dfrac{169}{104}\\ \dfrac{11}{13}=\dfrac{11.8}{13.8}=\dfrac{88}{104}\)
\(b,\dfrac{72}{64}=\dfrac{9}{8}\\ \dfrac{54}{81}=\dfrac{2}{3}\\ MSC:24\\ \dfrac{9}{8}=\dfrac{9.3}{8.3}=\dfrac{27}{24}\\ \dfrac{2}{3}=\dfrac{2.8}{3.8}=\dfrac{16}{24}\\ c,\dfrac{24}{36}=\dfrac{2}{3}\\ \dfrac{12}{30}=\dfrac{2}{5}\\ MSC:15\\ \dfrac{2}{3}=\dfrac{2.5}{3.5}=\dfrac{10}{15}\\ \dfrac{2}{5}=\dfrac{2.3}{3.5}=\dfrac{6}{15}\)
\(d,\dfrac{80}{40}=2\\ \dfrac{45}{63}=\dfrac{5}{7}\\ MSC:7\\ 2=\dfrac{14}{7}\\ e,\dfrac{150}{50}=3\\ \dfrac{100}{200}=\dfrac{1}{2}\\ MSC:2\\ 3=\dfrac{6}{2}\\ f,\dfrac{54}{81}=\dfrac{2}{3}\\ \dfrac{69}{93}=\dfrac{23}{21}\\ MSC:21\\ \dfrac{2}{3}=\dfrac{2.7}{3.7}=\dfrac{14}{21}\)
\(a.\dfrac{52}{32}\text{=}\dfrac{13}{8};\dfrac{55}{65}\text{=}\dfrac{11}{13}\)
\(\dfrac{13.13}{13.8}\text{=}\dfrac{169}{104};\dfrac{11.8}{13.8}\text{=}\dfrac{88}{104}\)
\(c.\dfrac{24}{36}\text{=}\dfrac{2}{3};\dfrac{12}{30}\text{=}\dfrac{2}{5}\)
\(\dfrac{2.5}{3.5}\text{=}\dfrac{10}{15};\dfrac{2.3}{5.3}\text{=}\dfrac{6}{15}\)
\(b.\dfrac{72}{64}\text{=}\dfrac{9.3}{8.3}\text{=}\dfrac{27}{24};\dfrac{54}{81}\text{=}\dfrac{2.8}{3.8}\text{=}\dfrac{16}{24}\)
\(d.\dfrac{80}{40}\text{=}\dfrac{2.63}{63}\text{=}\dfrac{126}{63};\dfrac{45}{63}\)
\(e.\dfrac{150}{50}\text{=}\dfrac{3.2}{2}\text{=}\dfrac{6}{2};\dfrac{100}{200}\text{=}\dfrac{1}{2}\)
\(f.\dfrac{54}{81}\text{=}\dfrac{2.31}{3.31}\text{=}\dfrac{62}{93};\dfrac{69}{93}\)
quá to nên tự rút r tự so sánh
A;18/27=2/3;24/56=3/7
Vay2/3<3/7
B36/90=2/5;50/125=2/5
2/5=2/5
C121/77=11/7;88/64=11/8
vai11/7co mau be hon 11/8 ma tu bang nhau nen
11/7>11/8
D52/91=4/7,60/84=5/7
phan so co mau bang nhau tu cua 5/7 lon hon4/7 nen 4/7<5/7
tich nha