a) 8kg 375g =8,375 kg

b)7m²28dm²=7,28 m²

c) 5dm 6cm = 5,6 dm

d) 4km²236hm²= 6,36km²

8,375

7,08

5,6

4,36

\(\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}+\dfrac{1}{64}+\dfrac{1}{128}\\ =\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{16}+...+\dfrac{1}{64}-\dfrac{1}{128}\\ =\dfrac{1}{2}-\dfrac{1}{128}\\ =\dfrac{63}{128}\)

\(7m^28dm^2=7,08m^2\)

c: =7,08

Đặt \(A=\dfrac{1}{4}+\dfrac{1}{8}+...+\dfrac{1}{128}\)

\(\Rightarrow A=\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^7}\\ \Rightarrow2A=\dfrac{1}{2}+\dfrac{1}{2^2}+...+\dfrac{1}{2^6}\\ \Rightarrow2A-A=\dfrac{1}{2}+\dfrac{1}{2^2}+...+\dfrac{1}{2^6}-\dfrac{1}{2^2}-\dfrac{1}{2^3}-...-\dfrac{1}{2^7}\\ \Rightarrow A=\dfrac{1}{2}-\dfrac{1}{2^7}=\dfrac{2^6-1}{2^7}=\dfrac{63}{128}\)

\(7m^28dm^2=7\dfrac{8}{100}m^2=7,08m^2\)

a) 15 cm2 + 20 cm2 = 35 cm2

60 cm2 - 42 cm2 = 18 cm2

20 cm2 + 10 cm2 + 15 cm2 = 45 cm2

b) 12 cm2 x 2 = 24 cm2

40 cm2 : 4 = 10 cm2

50 cm2 - 40 cm2 + 10 cm2 = 20 cm2

a) 4 m2 = 40000 cm2     m2 = 50dm2

16 m2 = 1600 dm2     dm2 = 50 cm2

308 dm2 = 30800cm2     m2 = 100 cm2

b) 700 cm2 = 7 dm2    15 m2 9 dm2 = 1509 dm2

3400 dm2 = 34 m2    7 dm2 25 cm2 = 725 cm2

50 000 cm2 = 5 m2    28 m2 50 cm2 = 280050 cm2

c) 948 dm2 = 9 m2 48 dm2    8791 dm2 = 87 m2 91 dm2

705 cm2 = 7 dm2 5cm2     30 045 cm2 = 3 m2 45 cm2

a 4 m² =40000 cm²

b 1/2 m² =50 dm ²

bằng  

4 m²=40000m²     

210  c m 2 = 2 d m 2  10 c m 2

1954 c m 2 > 19 d m 2  50 c m 2

6 d m 2  3 c m 2 = 603 c m 2

2001 c m 2 < 20 d m 2  10 c m 2

a) = 

b) >

c) =

d) <

210  c m 2 = 2 d m 2  10 c m 2

1954 c m 2 > 19 d m 2  50 c m 2

6 d m 2  3 c m 2 = 603 c m 2

2001 c m 2 < 20 d 2 10 c m 2

\(8cm^2+5cm^2=13cm^2\)

\(9cm^2\times3=27cm^2\)

\(37cm^2-20cm^2=17cm^2\)

\(36cm^2:4=9cm^2\)

a) 3 dm² = 300 cm²

300 cm² = 3 dm²

b) 6 dm² = 600 cm²

600 cm² = 6 dm²

6 dm² 50 cm² = 650 cm²