A) 1/2 . 4/3 - 20/3 . 4/5

= 2/3 - 16/3

= -14/3

B) 3/7+ -6/19 +4/7 + -13/19

=( 3/7+4/7) + ( -6/19 +-13/19)

=7/7+ 19/19

=1+(-1)

=0

C) 3/5. 8/9 - 7/9 . 3/5 + 3/5 . 29/9

=3/5 . ( 8/9 - 7/9+ 29/9)

=3/5 . 27/9

=3/5.3

=9/5

A) 1/2 . 4/3 - 20/3 . 4/5

= 2/3 - 16/3

= -14/3

B) 3/7+ -6/19 +4/7 + -13/19

=( 3/7+4/7) + ( -6/19 +-13/19)

=7/7+ 19/19

=1+(-1)

=0

C) 3/5. 8/9 - 7/9 . 3/5 + 3/5 . 29/9

=3/5 . ( 8/9 - 7/9+ 29/9)

=3/5 . 27/9

=3/5.3

=9/5

A) 1/2 . 4/3 - 20/3 . 4/5

= 2/3 - 16/3

= -14/3

B) 3/7+ -6/19 +4/7 + -13/19

=( 3/7+4/7) + ( -6/19 +-13/19)

=7/7+ 19/19

=1+(-1)

=0

C) 3/5. 8/9 - 7/9 . 3/5 + 3/5 . 29/9

=3/5 . ( 8/9 - 7/9+ 29/9)

=3/5 . 27/9

=3/5.3

=9/5

A) 1/2 . 4/3 - 20/3 . 4/5

= 2/3 - 16/3

= -14/3

B) 3/7+ -6/19 +4/7 + -13/19

=( 3/7+4/7) + ( -6/19 +-13/19)

=7/7+ 19/19

=1+(-1)

=0

C) 3/5. 8/9 - 7/9 . 3/5 + 3/5 . 29/9

=3/5 . ( 8/9 - 7/9+ 29/9)

=3/5 . 27/9

=3/5.3

=9/5

A) 1/2 . 4/3 - 20/3 . 4/5

= 2/3 - 16/3

= -14/3

B) 3/7+ -6/19 +4/7 + -13/19

=( 3/7+4/7) + ( -6/19 +-13/19)

=7/7+ 19/19

=1+(-1)

=0

C) 3/5. 8/9 - 7/9 . 3/5 + 3/5 . 29/9

=3/5 . ( 8/9 - 7/9+ 29/9)

=3/5 . 27/9

=3/5.3

=9/5

3 - 1/1.3 + 5 -3 + 7- 5/5.7+....+101-99/99.101

= 3/1.3 - 1/1.3+ 5/3.5 - 3/3.5 +7/5.7 - 5/5.7+.......+101/99.101 - 99/99.101

= 1- 1/3 + 1/3 -1/5 +1/5 -1/7+.....+1/99 - 1/101

= 1- 1/101=100/101

vay 2/1.3 +2/3.5+2/5.7+........+2/99.101=100/101

1. 

a) tap hop cac diem doan thang BD va B, C,D tap hop cac  diem thuoc ko doan thang BD va A, E

b) cap duong thang song song la AB//DE

c) cac cap duong thang cat nhau la : 

AB va AE cat nhau tai A

BA va BD cat nhau tai B

AE va BD cat nhau tai C

DEva DB cat nhau tai D

EA va ED cat nhau tai E

2. 

Do dai cua doan thang AB la :

6 - 4 = 2(cm)

Do dai cua doan thang AM la :

2: 2= 1(cm)

Do dai cua doan thang OM la :

4+1=5(cm)

Vay 5cm

a) so sanh ba phan so , ta duoc

5/27< 2/9 < 1/3

vay trong mot gio , doi thu ba lam duoc it phan cong viec nhat , doi thu hai la duoc nhieu cong viec nhat

b) neu lam trung , ca ba doi lam duoc 5/27+ 2/9+1/3= 20/27( cong viec)

A) X-2/3=-5/12

X=-5/12 +2/3

X= -5/12+8/12

X= 3/12

X= 1/4 

B)8/5: X=-2/3

X= 8/5: ( -2/3)

X= 8/5( 3/-2)

X=-12/5

C)1-3/7. X=-2/7

3/7. X=1-(-2/7)

3/7.X=9/7

X= 9/7: 3/7

X= 9/7. 3/7

X=3

 A)=-2/7+2/7x5/3

=-2/7+10/21

=-6/21+10/21

=4/21  

B) -8/19+-4/21-17/21 +27/19

=-8/19+-4/21+1721+27/19

=(-8/19+27/19) +(-4/21 +-17/21)

= -8+27/19+(-4)+(-17)/21

= 19/19+-21/21

= 1-1=0

C)6/5x3/13 - 6/5x16/13

= 6/5x(3/13 - 16/13)

= 6/5 x (3-16/13)

=6/5x(-13/13)

= 6/5x ( -1)

= -6/5