3*13-13*18=3*(3-18)=3*(-15)

15*40-80=15*(40-20)=15*20

\((-5)^3*10*4^3=(-5)^3*4^3*40 =(-20)^40 135*(-2)^14*(-100)= tự làm nhé k mk nha \)

5/7>6/21

18/24>15/25

12/13=1212/1313

\(\dfrac{5}{7}\)>\(\dfrac{6}{21}\)

\(\dfrac{18}{24}\)>\(\dfrac{15}{25}\)

\(\dfrac{12}{13}\)=\(\dfrac{1212}{1313}\)

Dùng latex

a: \(=\dfrac{54-34}{189-119}=\dfrac{20}{70}=\dfrac{2}{7}\)

b: \(=\dfrac{6+6\cdot4+6\cdot49}{15+15\cdot4+15\cdot49}=\dfrac{6}{15}=\dfrac{2}{5}\)

c: \(=\dfrac{13\left(3-18\right)}{40\left(15-2\right)}=\dfrac{-15}{40}=-\dfrac{3}{8}\)

a) \(\frac{-315}{540}=\frac{-7}{12}\)

b) \(\frac{25.13}{26.35}=\frac{5.1}{2.7}=\frac{5}{14}\)

c) \(\frac{6.9-2.17}{63.3-119}=\frac{2.1-2.17}{7.1-119}=\frac{2.\left(1-17\right)}{7.1-119}=\frac{2.\left(-16\right)}{7-119}=\frac{-32}{-112}=\frac{32}{112}=\frac{2}{7}\)

Làm đến đây là choáng r

Các câu típ theo bn làm nhé

d) 3.13-13.18/15.40-80 = 13.(3-18)/520= 13.(-15)/ 520 = -125/520=-3/8

2/7 ban nhe

chuc ban hoc tot

B

`=>B`

b

1a. chọn mẫu chung là 120,ta có

\(\frac{7}{30}=\frac{7.4}{30.4}=\frac{28}{120}\)

\(\frac{13}{60}=\frac{13.2}{60.2}=\frac{26}{120}\)

\(\frac{-9}{40}=\frac{-9.3}{40.3}=\frac{27}{120}\)

vậy....

1b. chon mẫu số chung là 60

\(\frac{3}{-20}=\frac{-3.3}{20.3}=-\frac{9}{60}\)

\(\frac{-11}{-30}=\frac{-11.\left(-2\right)}{-30.\left(-2\right)}=\frac{22}{60}\)

\(\frac{7}{15}=\frac{7.4}{15.4}=\frac{28}{60}\)

2a.\(\frac{-15}{90}=\frac{-1}{6};\frac{120}{600}=\frac{1}{5};\frac{-75}{150}=\frac{-1}{2}\)

mẫu chung 30

\(\frac{-1}{6}=-\frac{5}{30};\frac{1}{5}=\frac{16}{30};-\frac{1}{2}=\frac{-15}{30}\)

vậy...

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