Question

Câu 1. (2 điểm) Tính.

a) $\dfrac{1}{3}+\dfrac{3}{4}-\dfrac{5}{6}$ ;

b) $\dfrac{-2}{3}+\dfrac{6}{5}:\dfrac{2}{3}-\dfrac{2}{15}$ ;       

c) $\dfrac{-3}{7}+\dfrac{5}{13}+\dfrac{-4}{7}$ ;            

d) $\dfrac{12}{19}+\dfrac{-8}{13}-\dfrac{12}{19}+\dfrac{5}{-13}+2$ .

Answer 1

a) \(\frac{1}{3}+\frac{3}{4}-\frac{5}{6}\)

\(=\frac{1}{3}+\frac{3}{4}+\frac{-5}{6}\)

\(=\frac{1.4+3.3+\left(-5\right).2}{12}\)

\(=\frac{4+9+\left(-10\right)}{12}\)

\(=\frac{3}{12}\)

\(=\frac{1}{4}\)

Answer 2

b) \(\frac{-2}{3}+\frac{6}{5}\div\frac{2}{3}-\frac{2}{15}\text{ }\)

\(=\frac{-2}{3}+\frac{6}{5}\times\frac{3}{2}-\frac{2}{15}\)

\(=\frac{-2}{3}+\frac{18}{10}-\frac{2}{15}\)

\(=\frac{-2}{3}+\frac{9}{5}+\frac{-2}{15}\)

\(=\frac{\left(-2\right).5+9.3+\left(-2\right)}{15}\)

\(=\frac{\left(-10\right)+27+\left(-2\right)}{15}\)

\(=\frac{15}{15}\)

\(=1\)

Answer 3

c) \(\frac{-3}{7}+\frac{5}{13}+\frac{-4}{7}\text{ }\)

\(=\left(\frac{-3}{7}+\frac{-4}{7}\right)+\frac{5}{13}\)

\(=\frac{-7}{7}+\frac{5}{13}\)

\(=-1+\frac{5}{13}\)

\(=\frac{-13}{13}+\frac{5}{13}\)

\(=\frac{-8}{13}\)

Answer 4

d) \(\frac{12}{19}+\frac{-8}{13}-\frac{12}{19}+\frac{5}{-13}+2\text{ }\)

\(=\frac{12}{19}+\frac{-8}{13}+\frac{-12}{19}+\frac{-5}{13}+2\)

\(=\left(\frac{12}{19}+\frac{-12}{19}\right)+\left(\frac{-8}{13}+\frac{-5}{13}\right)+2\)

\(=0+\frac{-13}{13}+2\)

\(=0+\left(-1\right)+2\)

\(=-1\)

Answer 5

Answer 6

Answer 7

a) \dfrac{1}{3}+\dfrac{3}{4}-\dfrac{5}{6}31​+43​−65​

=\dfrac{4}{12}+\dfrac{9}{12}-\dfrac{10}{12}=124​+129​−1210​

=\dfrac{4+9-10}{12}=124+9−10​

=\dfrac{3}{12}=123​

=\dfrac{1}{4}=41​.

b) \dfrac{-2}{3}+\dfrac{6}{5}:\dfrac{2}{3}-\dfrac{2}{15}3−2​+56​:32​−152​

=\dfrac{-2}{3}+\dfrac{6}{5}.\dfrac{3}{2}-\dfrac{2}{15}=3−2​+56​.23​−152​

=\dfrac{-2}{3}+\dfrac{18}{10}-\dfrac{2}{15}=3−2​+1018​−152​

=\dfrac{-2}{3}+\dfrac{9}{5}-\dfrac{2}{15}=3−2​+59​−152​

=\dfrac{-10}{15}+\dfrac{27}{15}-\dfrac{2}{15}=15−10​+1527​−152​

=\dfrac{1}{3}=31​.

c) \dfrac{-3}{7}+\dfrac{5}{13}+\dfrac{-4}{7}7−3​+135​+7−4​

=\left( \dfrac{-3}{7}+\dfrac{-4}{7} \right)+\dfrac{5}{13}=(7−3​+7−4​)+135​

=\dfrac{-7}{7}+\dfrac{5}{13}=7−7​+135​

=-1+\dfrac{5}{13}=−1+135​

=\dfrac{-8}{13}=13−8​.

d) \dfrac{12}{19}+\dfrac{-8}{13}-\dfrac{12}{19}+\dfrac{5}{-13}+21912​+13−8​−1912​+−135​+2

=\dfrac{12}{19}+\dfrac{-8}{13}-\dfrac{12}{19}+\dfrac{-5}{13}+2=1912​+13−8​−1912​+13−5​+2

=\left( \dfrac{12}{19}-\dfrac{12}{19} \right)+\left( \dfrac{-8}{13}+\dfrac{-5}{13} \right)+2=(1912​−1912​)+(13−8​+13−5​)+2

=0+\dfrac{-13}{13}+2=0+13−13​+2

$=1$.

Answer 8

a) \dfrac{1}{3}+\dfrac{3}{4}-\dfrac{5}{6}31​+43​−65​

=\dfrac{4}{12}+\dfrac{9}{12}-\dfrac{10}{12}=124​+129​−1210​

=\dfrac{4+9-10}{12}=124+9−10​

=\dfrac{3}{12}=123​

=\dfrac{1}{4}=41​.

b) \dfrac{-2}{3}+\dfrac{6}{5}:\dfrac{2}{3}-\dfrac{2}{15}3−2​+56​:32​−152​

=\dfrac{-2}{3}+\dfrac{6}{5}.\dfrac{3}{2}-\dfrac{2}{15}=3−2​+56​.23​−152​

=\dfrac{-2}{3}+\dfrac{18}{10}-\dfrac{2}{15}=3−2​+1018​−152​

=\dfrac{-2}{3}+\dfrac{9}{5}-\dfrac{2}{15}=3−2​+59​−152​

=\dfrac{-10}{15}+\dfrac{27}{15}-\dfrac{2}{15}=15−10​+1527​−152​

=\dfrac{1}{3}=31​.

c) \dfrac{-3}{7}+\dfrac{5}{13}+\dfrac{-4}{7}7−3​+135​+7−4​

=\left( \dfrac{-3}{7}+\dfrac{-4}{7} \right)+\dfrac{5}{13}=(7−3​+7−4​)+135​

=\dfrac{-7}{7}+\dfrac{5}{13}=7−7​+135​

=-1+\dfrac{5}{13}=−1+135​

=\dfrac{-8}{13}=13−8​.

d) \dfrac{12}{19}+\dfrac{-8}{13}-\dfrac{12}{19}+\dfrac{5}{-13}+21912​+13−8​−1912​+−135​+2

=\dfrac{12}{19}+\dfrac{-8}{13}-\dfrac{12}{19}+\dfrac{-5}{13}+2=1912​+13−8​−1912​+13−5​+2

=\left( \dfrac{12}{19}-\dfrac{12}{19} \right)+\left( \dfrac{-8}{13}+\dfrac{-5}{13} \right)+2=(1912​−1912​)+(13−8​+13−5​)+2

=0+\dfrac{-13}{13}+2=0+13−13​+2

=1=1.

Answer 9

13+34−5613+34−56

=412+912−1012=412+912−1012

=4+9−1012=4+9−1012

=312=312

=14=14.

−23+65:23−215−23+65:23−215

=−23+65.32−215=−23+65.32−215

=−23+1810−215=−23+1810−215

=−23+95−215=−23+95−215

=−1015+2715−215=−1015+2715−215

=13=13.

−37+513+−47−37+513+−47

=(−37+−47)+513=(−37+−47)+513

=−77+513=−77+513

=−1+513=−1+513

=−813=−813.

1219+−813−1219+5−13+21219+−813−1219+5−13+2

=1219+−813−1219+−513+2=1219+−813−1219+−513+2

=(1219−1219)+(−813+−513)+2=(1219−1219)+(−813+−513)+2

=0+−1313+2=0+−1313+2

$=1$.

Answer 10

chịu

 

 

 

Answer 11

a)1/3+3/4-5/6=>4/12+9/12-10/12=>13/12-10/12=>3/12

 

Answer 12

1

Answer 13

a, 1/3 + 3/4 - 5/6 

=4/12 + 9/12 - 10/12

=4 + 9 - 10/ 2

=3/12 = 1/4

b, -2/3 + 6/5 : 2/3 - 2/15

=-2/3 + 6/5 . 3/2 - 2/15

=-2/3 + 18/10 - 2/15

=-2/3 + 9/5 - 2/15

=-10/15 + 27/15 - 2/15

=1/3

c,-3/7 + 5/13 + -4/7

= (-3/7 + -4/7) + 5/13

= -7/7 + 5/13 

=-1 + 5/13 = -3/13

d,12/19 + -8/13 - 12/19 + 5/-13 + 2

= 12/19 + -8/13 - 12/19 + -5/13 + 2

=(12/19 - 12/19) + (-8/13 + -5/13) + 2

=0 + -13/13 + 2 

=1

 

Answer 14

1/3+3/4-5/6

=13/2-5/6

=1/4

-2/3+6/5:2/3-2/15

=-2/3+6/5.3/2-2/15

=-2/3+18/10-2/15

=-2/3+9/5-2/15

=-10/15+27/15-2/15

=1/3

-3/7+5/13+(-4/7)

=[-3/7+(-4/7)]+5/13

=-7/7+5/13

=(-1)+5/13

=-8/13

12/19+(-8/13)-12/19+(-5/13)+2

=[12/19 -12/19]+[-8/13+(-5/13)]

=0+(-13/13)+2

=1

Answer 15

=1/3 +3/4 -5/6

=13/12 - 5/6

=1/4

-2/3 +5/6 :2/3 -2/15
=1/6+5/6:2/3-2/15

=1:2/3-2/15

=3/2-2/15
=1/5

-3/7+5/13+-5/7

=7/8+-5/7

=5/7

 

 

Answer 16

  

Answer 17

Answer 18

Answer 19

 

 

=0+\dfrac{-13}{13}+2

=1

Answer 20

Answer 21

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

=\(\dfrac{4}{12}+\dfrac{9}{12}-\dfrac{10}{12}\) 

=\(\dfrac{1}{4}\)   

=\(\dfrac{-2}{3}+\dfrac{6}{5}:\dfrac{2}{3}-\dfrac{2}{15}\) 

=\(\dfrac{-2}{3}+\dfrac{6}{5}.\dfrac{3}{2}-\dfrac{2}{15}\)

=\(\dfrac{-2}{3}+\dfrac{9}{5}-\dfrac{2}{15}\)

=\(\dfrac{-10}{15}-\dfrac{27}{15}-\dfrac{2}{15}\)

=\(\dfrac{1}{3}\)

c\(\dfrac{-3}{7}+\dfrac{5}{13}+\dfrac{-4}{7}\)

=(\(\dfrac{-3}{7}+\dfrac{-4}{7}\))+\(\dfrac{5}{13}\)

= -1+\(\dfrac{5}{13}\)    

=\(\dfrac{-13}{13}+\dfrac{5}{13}\)

=\(\dfrac{-8}{13}\)

d\(\dfrac{12}{19}+\dfrac{-8}{13}-\dfrac{12}{19}+\dfrac{5}{-13}+2\)

=(\(\dfrac{12}{19}-\dfrac{12}{19})+(\dfrac{-8}{13}+\dfrac{-5}{13})+2\)

=0+(-1)+2

=1

 

 

 

 

 

 

Answer 22

Answer 23

Answer 24

Answer 25

a)\(\dfrac{1}{3}+\dfrac{3}{4}-\dfrac{5}{6}=\dfrac{4}{12}+\dfrac{9}{12}-\dfrac{10}{12}=\dfrac{4+9-10}{12}=\dfrac{3}{12}=\dfrac{1}{4}\)

b)\(\dfrac{-2}{3}+\dfrac{6}{5}:\dfrac{2}{3}-\dfrac{2}{15}=\dfrac{-2}{3}+\dfrac{6}{5}.\dfrac{3}{2}-\dfrac{2}{15}=\dfrac{-2}{3}+\dfrac{18}{10}-\dfrac{2}{15}=\dfrac{-10}{15}+\dfrac{27}{15}-\dfrac{2}{15}=\dfrac{1}{3}\)

c)\(\dfrac{-3}{7}+\dfrac{5}{13}+\dfrac{-4}{7}=\dfrac{-3}{7}+\dfrac{-4}{7}+\dfrac{5}{13}=\dfrac{-7}{7}+\dfrac{5}{13}=-1+\dfrac{5}{13}=\dfrac{-8}{13}\)

d)\(\dfrac{12}{19}+\dfrac{-8}{13}-\dfrac{12}{19}+\dfrac{5}{-13}+2=\dfrac{12}{19}+\dfrac{-8}{13}-\dfrac{12}{19}+\dfrac{-5}{13}+2=\dfrac{12}{19}-\dfrac{12}{19}+\dfrac{-8}{13}+\dfrac{-5}{13}+2=0+\dfrac{-13}{13}+2=1\)

Answer 26

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Answer 27

111

Answer 28

a) \dfrac{1}{3}+\dfrac{3}{4}-\dfrac{5}{6}31​+43​−65​

=\dfrac{4}{12}+\dfrac{9}{12}-\dfrac{10}{12}=124​+129​−1210​

=\dfrac{4+9-10}{12}=124+9−10​

=\dfrac{3}{12}=123​

=\dfrac{1}{4}=41​.

b) \dfrac{-2}{3}+\dfrac{6}{5}:\dfrac{2}{3}-\dfrac{2}{15}3−2​+56​:32​−152​

=\dfrac{-2}{3}+\dfrac{6}{5}.\dfrac{3}{2}-\dfrac{2}{15}=3−2​+56​.23​−152​

=\dfrac{-2}{3}+\dfrac{18}{10}-\dfrac{2}{15}=3−2​+1018​−152​

=\dfrac{-2}{3}+\dfrac{9}{5}-\dfrac{2}{15}=3−2​+59​−152​

=\dfrac{-10}{15}+\dfrac{27}{15}-\dfrac{2}{15}=15−10​+1527​−152​

=\dfrac{1}{3}=31​.

c) \dfrac{-3}{7}+\dfrac{5}{13}+\dfrac{-4}{7}7−3​+135​+7−4​

=\left( \dfrac{-3}{7}+\dfrac{-4}{7} \right)+\dfrac{5}{13}=(7−3​+7−4​)+135​

=\dfrac{-7}{7}+\dfrac{5}{13}=7−7​+135​

=-1+\dfrac{5}{13}=−1+135​

=\dfrac{-8}{13}=13−8​.

d) \dfrac{12}{19}+\dfrac{-8}{13}-\dfrac{12}{19}+\dfrac{5}{-13}+21912​+13−8​−1912​+−135​+2

=\dfrac{12}{19}+\dfrac{-8}{13}-\dfrac{12}{19}+\dfrac{-5}{13}+2=1912​+13−8​−1912​+13−5​+2

=\left( \dfrac{12}{19}-\dfrac{12}{19} \right)+\left( \dfrac{-8}{13}+\dfrac{-5}{13} \right)+2=(1912​−1912​)+(13−8​+13−5​)+2

=0+\dfrac{-13}{13}+2=0+13−13​+2

$=1$.

Answer 29

Answer 30