a)  3 4 : 2 3 : 3 5 = 3 4 . 3 2 . 5 3 = 15 8

b)  3 4 : 2 3 : 3 5 = 3 4 : 2 3 . 5 3 = 3 4 : 10 9 = 3 4 . 9 10 = 27 40

a: =-3/24-40/24

=-43/24

b: \(=\dfrac{6}{54}\cdot\dfrac{49}{35}=\dfrac{1}{9}\cdot\dfrac{7}{5}=\dfrac{7}{45}\)

c: \(=\dfrac{6}{5}+\dfrac{4}{3}=\dfrac{18+20}{15}=\dfrac{38}{15}\)

d: \(=\dfrac{31}{17}-\dfrac{14}{17}-\dfrac{5}{13}-\dfrac{8}{13}=1-1=0\)

= 81

81

alo 

b: \(1024:2^5+140:\left(38+2^5\right)+2\cdot3^2-7^{23}:7^{21}\)

\(=1024:32+140:\left(38+32\right)+2\cdot9-7^2\)

=32+140:70+18-49

=50-49+2

=1+2

=3

c: \(100:\left\lbrace300:\left\lbrack450-\left(4\cdot5^3-2^3\cdot25\right)\right\rbrack\right\rbrace\)

\(=100:\left\lbrace300:\left\lbrack450-\left(4\cdot125-8\cdot25\right)\right\rbrack\right\rbrace\)

\(=100:\left\lbrace300:\left\lbrack450-\left(500-200\right)\right\rbrack\right\rbrace\)

=100:{300:[450-300]}

=100:{300:150}

=100:2

=50

Bài 2: Tính nhanh

a) 29 + 132 + 237 + 868 + 3

 = 29+(132+858)+(237+3)

=29+990+240

=1259

hình như bạn làm sai á

v

35 : 7 = 5

= 5

a)  − 1 10 + 3 5 + − 1 2 = − 1 10 + 6 10 + − 5 10 = 0

b) 

    3 8 + − 3 4 + 7 12 : 5 6 + 1 2 = 9 24 + − 18 24 + 14 24 : 5 6 + 1 2 = 5 24 ⋅ 6 5 + 1 2 = 1 4 + 1 2 = 3 4