C

C

bài 1:

các ps ....lớn đến bé là:

b1:8/10;14/20;27/40;5/8.

b2: (rút gọn)

5/8 ; 4/5 ; 7/10 ; 27/40.

a) \(\dfrac{16}{24};\dfrac{14}{15};\dfrac{25}{27};\dfrac{50}{100}\)
b) \(\dfrac{9}{4};\dfrac{5}{4};\dfrac{7}{5};\dfrac{19}{7};\dfrac{49}{36}\)
c) \(\dfrac{13}{13};\dfrac{35}{35}\)

a: 16/24; 14/15; 25/27; 50/100

b: 9/4; 5/4; 7/5; 19/7; 49/36

c: 13/13; 35/35

8/27+4/5+19/27+11/15=(8/27+19/27) + (4/5+11/15)

                                    = 1+ (12/15+11/15)

                                    = 1+ 1/8/15=2/8/15

12/13+2/7+8/13+6/13+5/7=(12/13+8/13+6/13) + (2/7+5/7)

                                         = 2+ 1

                                         =3

Ý a có thể bạn chép nhầm 4/5 rồi

= 2 + 1=3 nhé bạn

Bài 1:

a) 19/27+9/7+6/27+5/7+2/7

= (19/27+6/27) + (9/7+5/7+2/7)

=1 + 16/7

=23/7

b) 2/7 + 27/48 + 7/16 +45/63

= (2/7 + 45/63) + (27/48 +7/16)

= (2/7 + 5/7) + ( 9/16 + 7/16)

= 1 + 1

=2

c) Tính bằng cách bình thường

Bài 2:

6/11 + x = 1

           x = 1-6/11

           x = 5/11

Bài làm

a) \(\frac{19}{27}+\frac{9}{7}+\frac{6}{27}+\frac{5}{7}+\frac{2}{7}\)

\(=\frac{27}{27}+\frac{16}{7}\)

\(=1+\frac{16}{7}\)

\(=\frac{7}{7}+\frac{16}{7}\)

\(=\frac{23}{7}\)

b) \(\frac{2}{7}+\frac{27}{48}+\frac{7}{16}+\frac{45}{63}\)

\(=\left(\frac{18}{63}+\frac{45}{63}\right)+\left(\frac{27}{48}+\frac{21}{48}\right)\)

\(=\frac{63}{63}+\frac{48}{48}\)

\(=1+1\)

\(=2\)

c) \(\frac{17}{23}+\left(\frac{4}{7}-\frac{6}{13}\right)\)

\(=\frac{17}{23}+\left(\frac{52}{91}-\frac{42}{91}\right)\)

\(=\frac{17}{23}+\frac{10}{91}\)

\(=\frac{1547}{2093}+\frac{230}{2093}\)

\(=\frac{1770}{2093}\)

Bài 2

\(\frac{6}{11}+x=1\)

\(x=1-\frac{6}{11}\)

\(x=\frac{11}{11}-\frac{6}{11}=\frac{5}{11}\)

Vậy \(x=\frac{5}{11}\)

a)6/5+9/4=69/20

b)4/3-4/7=16/21

c)5/2*7/4=35/8

d)20/9:15/27=4

`3/7 + 4/5 + 4/7`

`= (3/7 +4/7)+4/5`

`= 7/7 +4/5`

`= 1 + 4/5`

`= 5/5 +4/5`

`=9/5`

`------`

`6/11 + 2/15 + 5/11`

`=(6/11 + 5/11)+2/15`

`= 1 + 2/15`

`= 15/15 +2/15`

`= 17/15`

`-----`

`4/9 + 2/5 + 15/27`

`= (4/9 + 15/27 )+2/5`

`= 1+2/5`

`=5/5 +2/5`

`=7/5`

`-----`

`6/13 + 9/32 + 21/26`

`= (6/13 + 21/26)+9/32`

`= ( 12/26 + 21/26)+9/32`

`= 33/26 +9/32`

`=645/416`

2

3

8/27+4/15+19/27+11/15

=(8/27+19/27)+(4/15+11/5)

=27/27+15/15

=1+1

=2

12/13 + 2/7 + 8/13 + 6/13 + 5/7

= ( 2/7 + 5/7 ) + ( 12/13 + 8/13 + 6/13 )

= 1 + 2

= 3