Bài 1: Làm quen với số nguyên âm

1: \(\dfrac{3}{-7}=\dfrac{-3}{7}=\dfrac{-3\cdot30}{7\cdot30}=\dfrac{-90}{210}\)

\(\dfrac{9}{21}=\dfrac{9\cdot10}{21\cdot10}=\dfrac{90}{210}\)

\(\dfrac{-6}{35}=\dfrac{-6\cdot6}{35\cdot6}=\dfrac{-36}{210}\)

2: \(\dfrac{-4}{15}=\dfrac{-4\cdot36}{15\cdot36}=\dfrac{-144}{540}\)

\(\dfrac{-7}{12}=\dfrac{-7\cdot45}{12\cdot45}=\dfrac{-315}{540}\)

\(\dfrac{8}{27}=\dfrac{8\cdot20}{27\cdot20}=\dfrac{160}{540}\)

3: \(\dfrac{-5}{16}=\dfrac{-5\cdot35}{16\cdot35}=\dfrac{-175}{560}\)

\(\dfrac{3}{-20}=\dfrac{-3}{20}=\dfrac{-3\cdot28}{20\cdot28}=\dfrac{-84}{560}\)

\(\dfrac{6}{28}=\dfrac{6\cdot20}{28\cdot20}=\dfrac{120}{560}\)

4: \(\dfrac{1}{42}=\dfrac{1\cdot10}{42\cdot10}=\dfrac{10}{420}\)

\(\dfrac{-7}{30}=\dfrac{-7\cdot14}{30\cdot14}=\dfrac{-98}{420}\)

\(-\dfrac{9}{12}=\dfrac{-9\cdot35}{12\cdot35}=\dfrac{-315}{420}\)

5: \(\dfrac{9}{-14}=\dfrac{-9}{14}=\dfrac{-9\cdot21}{14\cdot21}=\dfrac{-189}{294}\)

\(\dfrac{5}{42}=\dfrac{5\cdot7}{42\cdot7}=\dfrac{35}{294}\)

\(\dfrac{-3}{49}=\dfrac{-3\cdot6}{49\cdot6}=\dfrac{-18}{294}\)

6: \(\dfrac{-13}{45}=\dfrac{-13\cdot8}{45\cdot8}=\dfrac{-104}{360}\)

\(\dfrac{7}{15}=\dfrac{7\cdot24}{15\cdot24}=\dfrac{168}{360}\)

\(\dfrac{-3}{40}=\dfrac{-3\cdot9}{40\cdot9}=-\dfrac{270}{360}\)

7: \(\dfrac{2}{5}=\dfrac{2\cdot63}{5\cdot63}=\dfrac{126}{315}\)

\(\dfrac{13}{45}=\dfrac{13\cdot7}{45\cdot7}=\dfrac{91}{315}\)

\(\dfrac{-12}{35}=\dfrac{-12\cdot9}{35\cdot9}=\dfrac{-108}{315}\)

8: \(\dfrac{4}{17}=\dfrac{4\cdot6}{17\cdot6}=\dfrac{24}{102}\)

\(\dfrac{8}{51}=\dfrac{8\cdot2}{51\cdot2}=\dfrac{16}{102}\)

\(\dfrac{3}{34}=\dfrac{3\cdot3}{34\cdot3}=\dfrac{9}{102}\)

9: \(\dfrac{9}{13}=\dfrac{9\cdot30}{13\cdot30}=\dfrac{270}{390}\)

\(\dfrac{-6}{65}=\dfrac{-6\cdot6}{65\cdot6}=\dfrac{-36}{360}\)

\(\dfrac{-7}{39}=\dfrac{-7\cdot10}{39\cdot10}=-\dfrac{70}{390}\)

đề ở đâu bn

\(x=-\dfrac{6.2}{3}=-4\\ y=-\dfrac{14.3}{2}=-21\\ z=\dfrac{60.2}{3}=40\)

`@` `\text {Ans}`

`\downarrow`

`2323/3232 = 23/32`

`=> x = 23.`

`2323/3232 = (2323:101)/(3232:101) = 23/32`.

Vậy `x = 23.`

`2323/3232 = 23/32`

Đáp án: `-4,41`.

`3/5 = -0,6`.

`0,73 > 0 > -4,41`.

`1,56 > 0 > -4,41`.

Phân số đối của phân số âm 7 phần âm 9 là:\(\dfrac{9}{7}\)

Phân số đối của -7/-9 là -7/9

\(\dfrac{-7}{-9}=\dfrac{7}{9}\) có số đối là: \(\dfrac{9}{7}\)

1) Sai

2) Sai

3) Đúng

4) Sai

5) Sai

6) Sai

1.S

2.S

3.Đ

4.S

5.S

6.S

1) = (-4 + -6) +(440 -440)

  = -10

2) = (-56 - 64) + 263 + 483

  = -120 +  746 = -626

3) =(329 - 329) +64 +30 = 94

4) = (23 - 23) -10 = -10

5) =(215 -215) + 18 = 18

-30

số đối của 30 là -30 

\(-30\)