21 − 3 3 4 : 3 8 − 1 6 = 21 − 15 4 : 5 24 = 21 − 18 = 3

2 2 3 ⋅ 2 5 ⋅ 3 8 ⋅ 10 ⋅ 19 92 = 8 3 . 2 5 . 3 8 .10. 19 92 = 8.2.3.10.19 3.5.8.92 = 19 23

c) và d) của Trí sai nên sửa lại

c) (2x - 4)/7 < 0

⇒ 2x - 4 < 0 (vì 7 > 0)

⇒ 2x < 4

⇒ x < 2

d) (5x - 8)/-10 < 0

⇒ 5x - 8 > 0 (vì -10 < 0)

⇒ 5x > 8

⇒ x > 8/5

a) \(\dfrac{x-2}{45}>0\Rightarrow x-2>0\Rightarrow x>2\)

b) \(\dfrac{x+3}{-2}>0\Rightarrow x+3< 0\Rightarrow x< -3\)

c) \(\dfrac{2x-4}{7}< 0\Rightarrow2x-4>0\Rightarrow2x>4\Rightarrow x>2\)

d) \(\dfrac{5x-8}{10}< 0\Rightarrow5x-8< 0\Rightarrow5x< 8\Rightarrow x< \dfrac{8}{5}\)

A. 16/35 x -7/10= -8/25

B.12/5 : -15/2 = -8/25

a: \(-\dfrac{8}{25}=\dfrac{-7}{10}\cdot\dfrac{16}{35}\)

b: \(-\dfrac{8}{25}=\dfrac{12}{5}:\dfrac{-15}{2}\)

3,

a) $\left(\frac{-2}{3}+\frac{3}{7}\right):\frac{4}{5}+\left(\frac{-1}{3}+\frac{4}{7}\right):\frac{4}{5}$

= \(-\frac{5}{21}:\frac{4}{5}+\frac{5}{21}:\frac{4}{5}\)

= \(\left(-\frac{5}{21}+\frac{5}{21}\right):\frac{4}{5}\)

= \(0:\frac{4}{5}=0\)

2,

a) \(\frac{-3}{4}\))

= \(\frac{-3.4.3.\left(-5\right).5}{4.\left(-5\right).3.3}\)

= \(-5\)

b) ().\(\frac{-38}{21}\)

= \(\frac{19}{8}\)

c)

= \(\left(\frac{11}{12}.\frac{16}{33}\right).\frac{3}{5}\)

= \(\frac{4}{9}.\frac{3}{5}\)

= \(\frac{4}{15}\)

d) \(\frac{7}{23}\left[\left(\frac{-8}{6}\right)-\frac{45}{18}\right]\)

= \(\frac{7}{23}.\left(\frac{-41}{10}\right)\)

= \(\frac{-287}{203}\)

3. Tính:

a)

\(+\)\(\frac{-1}{3}+\frac{4}{7}\)) : \(\frac{4}{5}\)

= 0 : \(\frac{4}{5}\)

= 0

b) \(\frac{5}{9}\)\(\frac{5}{9}\)

: \(\frac{-3}{22}\)+ \(\frac{5}{9}\): \(\frac{-3}{5}\)

= \(\frac{5}{9}\): \(\frac{-81}{110}\)

= \(\frac{-550}{729}\)

Câu 6: 

=x⁸

giải ciup1 mik mấy câu kia lun ah

Cả 2 dạng

Ưm cả 2 dạng a và b đều đúng nha bn

Với câu b dấu bằng viết nhầm thành dấu cộng r bạn

Hok tốt !