= ( 64+36)+(58+22)+(67+33)

= 100 + 80 +100

= 100x2+80

= 200+80= 280

k mk nha

64 + 58 + 36 + 67 + 33 + 32

= ( 64 + 36 ) + ( 67 + 33 ) + ( 58 + 22 )

= 100 + 100 + 80

= 200 + 80

= 280

Tham khảo:

\(\dfrac{4}{7}-\dfrac{1}{3}< \dfrac{1}{2}-\dfrac{2}{9}\)

\(\dfrac{125}{100}-\dfrac{48}{64}< \dfrac{6}{7}-\dfrac{14}{28}\)

\(\dfrac{7}{5}-\dfrac{22}{25}=\dfrac{1}{5}+\dfrac{4}{10}\)\(\dfrac{45}{75}+\dfrac{22}{33}>\dfrac{4}{5}+\dfrac{4}{6}\)

Bài 1: 

150/120+15/27=5/4+5/9=45/36+20/36=65/36

42/49+56/84=6/7+2/3=9/21+14/21=23/21

22 x 22 = 16

11 x 11 = 4

33x33=36

44x44=64

22x22=16

11x11=4

\(\dfrac{-11}{22}\).\(\dfrac{-4}{33}\).\(\dfrac{84}{-25}\).\(\dfrac{5}{8}\)=\(\dfrac{-7}{18}\)

\(A=47.36+64.47+15\)

\(A=47.\left(36+64\right)+15\)

\(A=47.100+15\)

\(A=4700+15\)

\(A=4715\)

\(B=27+35+65+73+75\)

\(B=\left(27+73\right)+\left(35+65\right)+75\)

\(B=100+100+75\)

\(B=275\)

\(C=37+37.15+84.37\)

\(C=37.\left(1+15+84\right)\)

\(C=37.100\)

\(C=3700\)

\(D=\frac{1}{20.21}+\frac{1}{21.22}+\frac{1}{22.23}+\frac{1}{23.24}\)

\(D=\frac{1}{20}-\frac{1}{21}+\frac{1}{21}-\frac{1}{22}+\frac{1}{22}-\frac{1}{23}+\frac{1}{23}-\frac{1}{24}\)

\(D=\frac{1}{20}-\frac{1}{24}\)

\(D=\frac{24}{480}-\frac{20}{480}\)

\(D=\frac{4}{480}=\frac{1}{120}\)

\(E=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{49.50}\)

\(E=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}\)

\(E=1-\frac{1}{50}\)

\(E=\frac{49}{50}\)

a, \(64:2^3\) = \(2^6:2^3\) = \(2^3=8\)

b, \(7^5:343=7^5:7^3=7^2=49\)

c, \(243:3^3:3=3^5:3^3:3=3^{ }\)

bấm máy tính

bài 1:

gọi số lớn là a , số bé là b

Theo đề cho , ta có : 

a - b = 33 (1 )

\(\frac{a}{b}\) = 3  => a=3b (2)

Thay (2) vào (1) ta có :

a - b = 33 ↔ 3b - b = 33 ↔ 2b = 33 → b = 33 : 2 = 16,5

a = 3b → a = 3.16,5 = 49,5

Vậy số lớn là 49,5 

số bé là 16,5

bài 2 :

a) 58 . 75 + 58 . 50 - 58 . 25 

= 58 . ( 75 + 50 - 25 )

= 58 . 100 = 5800

b) 27 . 121 - 87 . 27 + 73 . 34 

= 27 . ( 121 - 87 ) + 73 . 34 

= 27 . 34 + 73 . 34

= 34 . ( 27 + 73 )

= 34. 100 = 3400