a: 7/8<8/9<9/10<10/11<11/12

b: 4/5<5/6<6/7<7/8

c: 1/3<3/5<7/9<9/11<11/13

Sắp sếp các số từ bé tới lớn 2/3 4/5 3/4

a, 5 + (-7) + 9 + (-11) + 13 + (-15)

=[(-7)+(-11)+(-15)] + (5 + 9 + 13)

=(-33)+27

=(-6)

b, (-6) + 8 + (-10) + 12 + (-14) + 16

=[(-6)+(-10)+(-14)]+ (8 + 12 + 16)

=(-30) + 36

=6

c, -298 + (-300)  + (-302)

= -598 + (-302)

=-890

A)

\(\frac{7}{12}+\frac{3}{4}\times\frac{2}{4}\)

\(=\frac{7}{12}\times\left(\frac{3}{4}+\frac{2}{4}\right)\)

\(=\frac{35}{48}\)

B)

\(\frac{8}{9}-\frac{4}{15}:\frac{2}{5}\)

\(=\frac{8}{9}-\frac{2}{3}\)

\(=\frac{6}{27}\)

`7/12 + 3/4 xx 2/9`

`= 7/12 + 6/36`

`= 7/12 + 1/6`

`= 7/12 + 2/12`

`= 9/12`

`= 3/4`

__

`8/9 - 4/15 : 2/5`

`= 8/9- 4/15 xx 5/2`

`= 8/9 - 20/30`

`= 8/9- 2/3`

`= 8/9- 6/9`

`= 2/9`

a)

`7/12+3/4xx2/9`

`=7/12+1/6`

`=7/12+2/12`

`=9/12`

`=3/4`

b)

`8/9-4/15:2/5`

`=8/9-4/15xx5/2`

`=8/9-2/3`

`=8/9-6/9`

`=2/9`

ai làm đúng e tích đúng cho

\(x=\dfrac{4}{7}:\dfrac{3}{5}=\dfrac{4\times5}{7\times3}=\dfrac{20}{21}\)

=>x=4/7:3/5

x=4/7 x 5/3

x=20/21

\(\dfrac{3}{5}\times x=\dfrac{4}{7}\\ x=\dfrac{4}{7}:\dfrac{3}{5}\\ x=\dfrac{4}{7}\times\dfrac{5}{3}\\ x=\dfrac{20}{21}\)

5/8+4/9

=45/72+32/72

=77/72

\(\dfrac{5}{8}+\dfrac{4}{9}=\dfrac{45}{72}+\dfrac{32}{72}=\dfrac{77}{72}\)

77/72

Câu 2: 

a: \(1DE_{16}=478_{10}\)

c: \(65_{10}=\text{1000001}_2\)

( 7/4+5/4) x 5/3= 12/4 x 5/3 = 3 x 5/3= 5

5

5