So sánh hai phân số:
a) \(\dfrac{5}{9}\) và \(\dfrac{7}{9}\) b) \(\dfrac{7}{6}\) và \(\dfrac{6}{6}\) c) \(\dfrac{3}{14}\) và \(\dfrac{5}{14}\) d) \(\dfrac{5}{8}\) và \(\dfrac{9}{8}\)
So sánh hai phân số:
a) \(\dfrac{5}{9}\) và \(\dfrac{7}{9}\) b) \(\dfrac{7}{6}\) và \(\dfrac{6}{6}\) c) \(\dfrac{3}{14}\) và \(\dfrac{5}{14}\) d) \(\dfrac{5}{8}\) và \(\dfrac{9}{8}\)
a) \(\dfrac{5}{9}< \dfrac{7}{9}\)
b) \(\dfrac{7}{6}>\dfrac{6}{6}\)
c) \(\dfrac{3}{14}< \dfrac{5}{14}\)
d) \(\dfrac{5}{8}< \dfrac{9}{8}\)
a)\(\dfrac{7}{8}\)x\(\dfrac{3}{13}\)+\(\dfrac{4}{9}\)x\(\dfrac{4}{13}\)
b)\(\dfrac{6}{5}\)+\(\dfrac{7}{3}\)+\(\dfrac{8}{9}\)
c)23: \(\dfrac{5}{14}\)+\(\dfrac{6}{7}\)+\(\dfrac{4}{9}\)
d)\(4\dfrac{1}{4}\)+\(7\dfrac{3}{7}\)-\(2\dfrac{4}{17}\)
e)8-(9\(\dfrac{2}{11}\)+\(\dfrac{8}{33}\))
a, \(\dfrac{7}{8}\) \(\times\) \(\dfrac{3}{13}\) + \(\dfrac{4}{9}\) \(\times\) \(\dfrac{4}{13}\)
= \(\dfrac{1}{13}\) \(\times\)( \(\dfrac{21}{8}\) + \(\dfrac{16}{9}\))
= \(\dfrac{1}{13}\) \(\times\)( \(\dfrac{189}{72}\) + \(\dfrac{128}{72}\))
= \(\dfrac{1}{13}\) \(\times\) \(\dfrac{317}{73}\)
= \(\dfrac{317}{949}\)
b, \(\dfrac{6}{5}\) + \(\dfrac{7}{3}\) + \(\dfrac{8}{9}\)
= \(\dfrac{54}{45}\) + \(\dfrac{105}{45}\) + \(\dfrac{40}{45}\)
= \(\dfrac{199}{45}\)
c, 23 : \(\dfrac{5}{14}\) + \(\dfrac{6}{7}\) + \(\dfrac{4}{9}\)
= \(\dfrac{322}{5}\) + \(\dfrac{6}{7}\) + \(\dfrac{4}{9}\)
= \(\dfrac{20286}{315}\) + \(\dfrac{270}{315}\) + \(\dfrac{140}{315}\)
= \(\dfrac{20696}{315}\)
d, 4\(\dfrac{1}{4}\) + 7\(\dfrac{3}{7}\) - 2\(\dfrac{4}{17}\)
= 4 + \(\dfrac{1}{4}\) + 7 + \(\dfrac{3}{7}\) - 2 - \(\dfrac{4}{17}\)
= (4+7-2) + (\(\dfrac{1}{4}\) + \(\dfrac{3}{7}\) - \(\dfrac{4}{17}\))
= 9 + \(\dfrac{119}{476}\) + \(\dfrac{204}{476}\) - \(\dfrac{112}{476}\)
= 9\(\dfrac{211}{476}\) = \(\dfrac{4495}{476}\)
e, 8 - (9\(\dfrac{2}{11}\) + \(\dfrac{8}{33}\))
= 8 - 9 - \(\dfrac{2}{11}\) - \(\dfrac{8}{33}\)
= -1 - \(\dfrac{2}{11}\) - \(\dfrac{8}{33}\)
= \(\dfrac{-33}{33}\) - \(\dfrac{-6}{33}\) - \(\dfrac{8}{33}\)
= - \(\dfrac{47}{33}\)
Tính rồi so sánh.
a) \(\dfrac{2}{9}+\dfrac{5}{9}\) và \(\dfrac{5}{9}+\dfrac{2}{9}\) b) \(\dfrac{3}{25}+\dfrac{4}{25}+\dfrac{7}{25}\) và \(\dfrac{3}{25}+\dfrac{7}{25}+\dfrac{4}{25}\)
a) \(\dfrac{2}{9}+\dfrac{5}{9}=\dfrac{7}{9};\dfrac{5}{9}+\dfrac{2}{9}=\dfrac{7}{9}\)
Vậy: \(\dfrac{2}{9}+\dfrac{5}{9}=\dfrac{5}{9}+\dfrac{2}{9}\)
b) \(\dfrac{3}{25}+\dfrac{4}{25}+\dfrac{7}{25}=\dfrac{14}{25};\dfrac{3}{25}+\dfrac{7}{25}+\dfrac{4}{25}=\dfrac{14}{25}\)
Vậy: \(\dfrac{3}{25}+\dfrac{4}{25}+\dfrac{7}{25}=\dfrac{3}{25}+\dfrac{7}{25}+\dfrac{4}{25}\)
cặp phân số nào bằng nhau :
\(A\) \(\dfrac{-3}{4}\)và \(\dfrac{-4}{3}\)
B \(\dfrac{-2}{3}\)và\(\dfrac{6}{9}\)
C 3/7 và \(\dfrac{-3}{7}\)
D 7/8 và \(\dfrac{-35}{-40}\)
So sánh hai phân số
a ) \(\dfrac{23}{24}\)và \(\dfrac{24}{23}\) b ) \(\dfrac{4}{21}\)và \(\dfrac{6}{29}\) c ) \(\dfrac{6}{7}\)và \(\dfrac{8}{9}\) d )\(\dfrac{1212}{1313}\)và \(\dfrac{12}{13}\)
giúp mik nha
a) \(\dfrac{23}{24}< 1\)
\(\dfrac{24}{23}>1\)
\(\Rightarrow\dfrac{23}{24}< \dfrac{24}{23}\)
b) \(\dfrac{4}{21}< \dfrac{4}{20}=\dfrac{1}{5}=\dfrac{6}{30}< \dfrac{6}{29}\)
c) \(\dfrac{6}{7}=1-\dfrac{1}{7}< \dfrac{8}{9}=1-\dfrac{1}{9}\)
d) \(\dfrac{1212}{1313}=\dfrac{12\times101}{13\times101}=\dfrac{12}{13}\)
1. <, >, =
\(\dfrac{14}{7}\) ...... \(\dfrac{9}{7}\)
\(\dfrac{6}{13}\) ....... 1
\(\dfrac{7}{9}\)..........\(\dfrac{14}{18}\)
\(\dfrac{4}{9}\)........ \(\dfrac{26}{45}\)
\(\dfrac{11}{24}\)........ \(\dfrac{3}{8}\)
\(\dfrac{42}{91}\)....... \(\dfrac{7}{13}\)
\(\dfrac{34}{64}\)........... \(\dfrac{13}{16}\)
\(\dfrac{17}{30}\).......... \(\dfrac{8}{15}\)
2.
\(\dfrac{14}{7}>\dfrac{9}{7}\)
\(\dfrac{6}{13}< 1\)
\(\dfrac{7}{9}=\dfrac{14}{18}\)
\(\dfrac{4}{9}=\dfrac{20}{45}< \dfrac{26}{45}\)
\(\dfrac{11}{24}>\dfrac{9}{24}=\dfrac{3}{8}\)
\(\dfrac{42}{91}=\dfrac{42:7}{91:7}=\dfrac{6}{13}< \dfrac{7}{13}\)
\(\dfrac{34}{64}< \dfrac{52}{64}=\dfrac{13}{16}\)
\(\dfrac{17}{30}>\dfrac{16}{30}=\dfrac{8}{15}\)
\(\dfrac{-2}{9}\)và\(\dfrac{6}{-27}\) b:\(\dfrac{-1}{-5}\)và\(\dfrac{4}{25}\)
Các cặp phân số sau có bằng nhau ko?vì sao?
Bài3: Tìm số nguyên X biết
a)\(\dfrac{-28}{35}\)=\(\dfrac{16}{x}\)
b)\(\dfrac{x+7}{15}\)=\(\dfrac{-24}{36}\)
giúp mình với ae cứu tôi ae cứu tôi :((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
Bài 2:
a: -2*(-27)=54
6*9=54
=>Hai phân số này bằng nhau
b: -1/-5=1/5=5/25<>4/25
Bài 3:
a: =>16/x=-4/5
=>x=-20
b: =>(x+7)/15=-2/3
=>x+7=-10
=>x=-17
a) \(\dfrac{-2}{9}\) và \(\dfrac{6}{-27}\)
\(\dfrac{6}{-27}=\dfrac{6:\left(-3\right)}{\left(-27\right):\left(-3\right)}=\dfrac{-2}{9}\)
Vậy \(\dfrac{-2}{9}=\dfrac{6}{-27}\)
b) \(\dfrac{-1}{-5}\) và \(\dfrac{4}{25}\)
\(\dfrac{-1}{-5}=\dfrac{\left(-1\right).\left(-5\right)}{\left(-5\right).\left(-5\right)}=\dfrac{5}{25}\)
Do \(5\ne4\Rightarrow\dfrac{5}{25}\ne\dfrac{4}{25}\)
Vậy \(\dfrac{-1}{-5}\ne\dfrac{4}{25}\)
Bài 3
a) \(\dfrac{-28}{35}=\dfrac{16}{x}\)
\(x=\dfrac{35.16}{-28}\)
\(x=-20\)
b) \(\dfrac{x+7}{15}=\dfrac{-24}{36}\)
\(\left(x+7\right).36=15.\left(-24\right)\)
\(36x+252=-360\)
\(36x=-360-252\)
\(36x=-612\)
\(x=\dfrac{-612}{36}\)
\(x=-17\)
a)\(\dfrac{-3}{7}+\dfrac{15}{26}-\left(\dfrac{2}{13}-\dfrac{3}{7}\right)\)
b)\(2.\dfrac{3}{7}+\left(\dfrac{2}{9}-1\dfrac{3}{7}\right)-\dfrac{5}{3}:\dfrac{1}{9}\)
c)\(\dfrac{-11}{23}.\dfrac{6}{7}+\dfrac{8}{7}.\dfrac{-11}{23}-\dfrac{1}{23}\)
d)\(\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right).\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{24}\right)\)
nhanh lên giúp mình vs
a) Ta có: \(\dfrac{-3}{7}+\dfrac{15}{26}-\left(\dfrac{2}{13}-\dfrac{3}{7}\right)\)
\(=\dfrac{-3}{7}+\dfrac{15}{26}-\dfrac{2}{13}+\dfrac{3}{7}\)
\(=\dfrac{15}{26}-\dfrac{4}{26}\)
\(=\dfrac{11}{26}\)
b) Ta có: \(2\cdot\dfrac{3}{7}+\left(\dfrac{2}{9}-1\dfrac{3}{7}\right)-\dfrac{5}{3}:\dfrac{1}{9}\)
\(=\dfrac{6}{7}+\dfrac{2}{9}-\dfrac{10}{7}-\dfrac{5}{3}\cdot9\)
\(=\dfrac{-4}{7}+\dfrac{2}{9}-15\)
\(=\dfrac{-36}{63}+\dfrac{14}{63}-\dfrac{945}{63}\)
\(=\dfrac{-967}{63}\)
c) Ta có: \(\dfrac{-11}{23}\cdot\dfrac{6}{7}+\dfrac{8}{7}\cdot\dfrac{-11}{23}-\dfrac{1}{23}\)
\(=\dfrac{-11}{23}\cdot\left(\dfrac{6}{7}+\dfrac{8}{7}\right)-\dfrac{1}{23}\)
\(=\dfrac{-11}{23}\cdot2-\dfrac{1}{23}\)
\(=-1\)
d) Ta có: \(\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{24}\right)\)
\(=\left(\dfrac{-377}{231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot\left(\dfrac{4}{24}-\dfrac{3}{24}-\dfrac{1}{24}\right)\)
\(=\left(\dfrac{-377}{231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot0\)
=0
Quy đồng mẫu số các phân số (theo mẫu).
Mẫu: \(\dfrac{5}{7}\) và \(\dfrac{9}{14}\) \(\dfrac{5}{7}=\dfrac{5\times2}{7\times2}=\dfrac{10}{14}\) |
a) \(\dfrac{5}{9}\) và \(\dfrac{11}{18}\) b) \(\dfrac{13}{60}\) và \(\dfrac{9}{20}\)
Lời giải:
a. $\frac{5}{9}=\frac{5\times 2}{9\times 2}=\frac{10}{18}$
b. $\frac{9}{20}=\frac{9\times 3}{20\times 3}=\frac{27}{60}$
a) \(\dfrac{5}{9}=\dfrac{5\times2}{9\times2}=\dfrac{10}{18}\)
b) \(\dfrac{9}{20}=\dfrac{9\times3}{20\times3}=\dfrac{27}{60}\)
Tính nhanh:
a) \(2.\dfrac{3}{7}+\left(\dfrac{2}{9}-1\dfrac{3}{7}\right)-\dfrac{5}{3}:\dfrac{1}{9}\)
b) \(\dfrac{-11}{23}.\dfrac{6}{7}+\dfrac{8}{7}.\dfrac{-11}{23}-\dfrac{1}{23}\)
c) \(\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right).\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{24}\right)\)
d) \(19\dfrac{5}{8}:\dfrac{7}{12}-15\dfrac{1}{4}:\dfrac{7}{12}\)
e) \(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}\)