a: \(12\dfrac{1}{3}-\left(3\dfrac{3}{4}+4\dfrac{3}{4}\right)\)

\(=\dfrac{37}{3}-3-4-\dfrac{3}{2}\)

\(=\dfrac{74-9}{6}-7=\dfrac{65}{6}-7=\dfrac{65-42}{7}=\dfrac{23}{7}\)

b: \(3\dfrac{5}{6}+2\dfrac{1}{6}\cdot6\)

\(=3+\dfrac{5}{6}+\dfrac{13}{6}\cdot6\)

\(=16+\dfrac{5}{6}=\dfrac{101}{6}\)

c: \(3\dfrac{1}{2}+4\dfrac{5}{7}-5\dfrac{5}{14}\)

\(=3+\dfrac{1}{2}+4+\dfrac{5}{7}-5-\dfrac{5}{14}\)

\(=2+\dfrac{7+10-5}{14}=2+\dfrac{12}{14}=2+\dfrac{6}{7}=\dfrac{20}{7}\)

d: \(=\dfrac{9}{2}+\dfrac{1}{2}:\dfrac{11}{2}=\dfrac{9}{2}+\dfrac{1}{11}=\dfrac{99+2}{22}=\dfrac{101}{22}\)

các bn giải mk nha

Chọn B

C

Chọn A

A

b: \(\left[\left(6+\dfrac{3}{5}-3-\dfrac{3}{14}\right)\cdot\dfrac{2}{5}\right]:\left(21-1.25\right)=x:\left(5+\dfrac{5}{6}\right)\)

\(\Leftrightarrow x:\dfrac{35}{6}=\dfrac{237}{175}:\dfrac{79}{4}\)

\(\Leftrightarrow x:\dfrac{35}{6}=\dfrac{12}{175}\)

\(\Leftrightarrow x=\dfrac{2}{5}\)

a) \(3\dfrac{1}{2}-1\dfrac{1}{4}\times1\dfrac{5}{6}\)

\(=\dfrac{7}{2}-\dfrac{5}{4}\times\dfrac{11}{6}\)

\(=\dfrac{7}{2}-\dfrac{55}{24}\)

\(=\dfrac{84}{24}-\dfrac{55}{24}\)

\(=\dfrac{29}{24}\)

b) \(2\dfrac{5}{6}+1\dfrac{2}{3}\div3\dfrac{3}{4}\)

\(=\dfrac{17}{6}+\dfrac{5}{3}\div\dfrac{15}{4}\)

\(=\dfrac{17}{6}+\dfrac{5}{3}\times\dfrac{4}{15}\)

\(=\dfrac{17}{6}+\dfrac{4}{9}\)

\(=\dfrac{153}{54}+\dfrac{24}{54}\)

\(=\dfrac{59}{18}\)

a) 312−114×156321​−141​×165​

=72−54×116=27​−45​×611​

=72−5524=27​−2455​

=8424−5524=2484​−2455​

=2924=2429​
 

b) 256+123÷334265​+132​÷343​

=176+53÷154=617​+35​÷415​

=176+53×415=617​+35​×154​

=176+49=617​+94​

=15354+2454=54153​+5424​

=5918=

a) \(\dfrac{6}{7}=\dfrac{6\times11}{7\times11}=\dfrac{66}{77}\)  ;   \(\dfrac{5}{11}=\dfrac{5\times7}{11\times7}=\dfrac{35}{77}\)

b) \(\dfrac{5}{9}=\dfrac{5\times5}{9\times5}=\dfrac{25}{45}\)    ;   \(\dfrac{9}{5}=\dfrac{9\times9}{5\times9}=\dfrac{81}{45}\)

c) \(\dfrac{3}{8}=\dfrac{3\times3}{8\times3}=\dfrac{9}{24}\)    ;    \(\dfrac{5}{24}\) giữ nguyên phân số

d) \(\dfrac{6}{5}=\dfrac{6\times6}{5\times6}=\dfrac{36}{30}\)    ;     \(\dfrac{5}{6}=\dfrac{5\times5}{6\times5}=\dfrac{25}{30}\)

\(#Wendy.Dang\)

a) 6/7 và 5/11

ta có :

6/7=66/77

5/11=35/77

b)5/9 và 9/5

ta có 

5/9=25/45

9/5=81/45

C)3/8 và 5/24

ta có :

3/8=9/24

5/24

D)6/5 và 5/6

ta có 

6/5=36/30

5/6=25/30

Câu 12: Ko có câu nào đúng

\(a,\dfrac{5}{3}>\dfrac{3}{5};b,\dfrac{6}{11}< \dfrac{9}{5};c,\dfrac{6}{11}=\dfrac{6}{11};d,\dfrac{8}{9}< \dfrac{8}{5}\)

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