Bài 1:

a, 3\(\dfrac{2}{5}\) - \(\dfrac{1}{2}\) 

= \(\dfrac{17}{5}\) - \(\dfrac{1}{2}\) 

= \(\dfrac{34}{10}\) - \(\dfrac{5}{10}\)

= \(\dfrac{29}{10}\)

b, \(\dfrac{4}{5}\) + \(\dfrac{1}{5}\) x \(\dfrac{3}{4}\)

= \(\dfrac{4\times4}{5\times4}\) + \(\dfrac{1\times3}{5\times4}\)

= \(\dfrac{16}{20}\) + \(\dfrac{3}{20}\)

= \(\dfrac{19}{20}\)

c, 4\(\dfrac{4}{9}\) : 2\(\dfrac{2}{3}\) + 3\(\dfrac{1}{6}\)

= \(\dfrac{40}{9}\) : \(\dfrac{8}{3}\) + \(\dfrac{19}{6}\)

= \(\dfrac{5}{3}\) + \(\dfrac{19}{6}\)

= \(\dfrac{10}{6}\) + \(\dfrac{19}{6}\)

= \(\dfrac{29}{6}\)

Bài 2:

   3\(\dfrac{2}{5}\) + 2\(\dfrac{1}{5}\) 

= \(\dfrac{17}{5}\) + \(\dfrac{11}{5}\)

= \(\dfrac{28}{5}\)

b, 7\(\dfrac{1}{6}\) : 5\(\dfrac{2}{3}\)

= \(\dfrac{43}{6}\) : \(\dfrac{17}{3}\)

= \(\dfrac{43}{34}\)

Bài 3:

a, 800 kg 5g > 8,005 kg

b, 9 ha 4 dam² < 9\(\dfrac{5}{100}\) ha

c, 5m 5mm > 5,0005 m

d, 250 kg > \(\dfrac{1}{5}\) tấn

a. 

\(\left(1\frac{1}{4}+\frac{3}{5}\right):\left(-\frac{11}{12}\right)+\left(\frac{3}{8}-1\frac{2}{5}\right):\left(-\frac{11}{12}\right)\) 

\(=\left(\frac{5}{4}+\frac{3}{5}+\frac{3}{8}-\frac{7}{5}\right):\left(-\frac{11}{12}\right)\)  

\(=\left(\frac{13}{8}-\frac{4}{5}\right):\left(-\frac{11}{12}\right)\) 

\(=\frac{33}{40}:\left(-\frac{11}{12}\right)\) 

\(=\frac{33}{40}\cdot\left(-\frac{12}{11}\right)\) 

\(=\frac{-9}{10}\)  

b. 

\(\left(\frac{3}{8}-1\frac{2}{5}\right):\left(-\frac{11}{15}\right)+\left(1\frac{1}{4}+\frac{3}{5}\right):\left(-\frac{11}{15}\right)\) 

\(=\left(\frac{3}{8}-\frac{7}{5}+\frac{5}{4}+\frac{3}{5}\right):\left(-\frac{11}{15}\right)\)  

\(=\left(\frac{13}{8}-\frac{4}{5}\right):\left(-\frac{11}{15}\right)\) 

\(=\frac{33}{40}:\left(-\frac{11}{15}\right)\) 

\(=\frac{33}{40}\cdot\left(-\frac{15}{11}\right)\) 

\(=\frac{-9}{8}\)

Tính:

2/7 + 5/7=1          

8/15 + 6/15 =14/15         

2/9 + 3/9 + 4/9=9/9=1

[ Không cần làm phép tính ]Điền vào ô trống <,>,= :

3/5 + 1/5 = 1/5 + 3/5

7/9 + 1/9 < 7/9 + 1/9 + 1/9

3/7 + 2/7 < 3/7 + 4/7

1/5 + 3/5 < 2/5 + 3/5

Tính:

2/7 + 5/7=1          

8/15 + 6/15 =14/15         

2/9 + 3/9 + 4/9=9/9=1

[ Không cần làm phép tính ]Điền vào ô trống <,>,= :

3/5 + 1/5 = 1/5 + 3/5

7/9 + 1/9 < 7/9 + 1/9 + 1/9

3/7 + 2/7 < 3/7 + 4/7

1/5 + 3/5 < 2/5 + 3/5

5 - 1 = 4     1 + 4 = 5     2 + 3 = 5

5 - 2 = 3     4 + 1 = 5     3 + 2 = 5

5 - 3 = 2     5 - 1 = 4     5 - 2 = 3

5 - 4 = 1     5 - 4 = 1     5 - 3 = 2

5-1=4     1+4=5     2+3=5

5-2=3     4+1=4     3+2=5

5-3=2     5-1=4      5-2=3

5-4=1     5-4=1      5-3=2

c/
C = 1/100-1/100-1/99-1/99-1/98-1/98-1/97-..........-1/3-1/2-1/2-1/1
C = 1/100-1/100-1/1
C = 0-1/1
C = -1

2 - 1 = 1     3 - 2 = 1     4 - 3 = 1     5 - 4 = 1

3 - 1 = 2     4 - 2 = 2     5 - 3 = 2

4 - 1 = 3     5 - 2 = 3

5 - 1 = 4

Lời giải chi tiết: 

Lời giải chi tiết: