a: 14/5-7/5=7/5

b: 7/8-1/3+5/4

=21/24-8/24+30/24

=43/24

c; =7/6+5/6+2/15+13/15

=2+1

=3

d: =4*5/3*11=20/33

e: =2/9*1/6*1/4=2/9*1/24=1/108

2:
a: \(=\dfrac{3}{9}\cdot\dfrac{4}{4}\cdot\dfrac{5}{5}\cdot\dfrac{6}{6}\cdot\dfrac{7}{7}=\dfrac{1}{3}\)

b: \(=\dfrac{1}{6}\left(\dfrac{22}{3}-\dfrac{2}{3}\right)=\dfrac{10}{3}\cdot\dfrac{1}{6}=\dfrac{10}{18}=\dfrac{5}{9}\)

c; \(=\dfrac{1}{3}\left(9-\dfrac{2}{5}-\dfrac{3}{5}\right)=\dfrac{8}{3}\)

14/5-7/5=7/5 

7/8-1/3+5/4=13/24+5/4=43/24 

7/6+2/15+5/6+13/15=13/10+5/6+13/15=32/15+13/15=3

4/3*5/11=20/35

2/9:6*1/4=1/27*1/4=1/108

(3/5+2/5)+(19/13+7/13)+(5/1+16/11)

1+2+5+16/11

8+16/11

TỰ TÍNH

12/13

=3/1.4  + 3/4.7 + 3/7.10 + 3/13.10

=1/1 - 1/4 + 1/4 + 1/7 + 1/7 + 1/10 + 1/10 -  1/13

=8+4/13

=12/13

= \(\dfrac{3}{1.4}+\dfrac{3}{4.7}+\dfrac{3}{7.10}+\dfrac{3}{10.13}\) 

= \(1-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{10}+\dfrac{1}{10}-\dfrac{1}{13}=1-\dfrac{1}{13}=\dfrac{12}{13}\)

7: =-1+8=7

6: \(=-\left(8\cdot125\right)\cdot\left(2\cdot5\right)\cdot\left(25\cdot4\right)=-1000000\)

5: =-50+19+143+79-25-48

=-75+98+95

=23+95

=118

4: =37x9+17x9-35x9-35x11

=18+153-385

=-214

3: =187-23-20+180

=367-43

=324

4: \(=37\cdot9+17\cdot9-35\cdot9-35\cdot11=19\cdot9-385\)

\(=171-385=-214\)

5: =-50+19+143+79-25-48

=-75+94+95

=20+94

=114

3 ; 324

4 ; -214

5 ; 118

6 ; - 1 000 000

7 ; 7

học tốt

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

Lời giải chi tiết: 

5-1=4     4-1=3    3-1=2   2+3=5     

5-2=3     4-2=2    3-2=1   3+2=5

5-3=2     4-3=1    2-1=1   5-2=3

5-4=1                               5-3=2

Tính:

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

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