\(\dfrac{33}{38}:\dfrac{11}{19}=\dfrac{33\times19}{38\times11}=\dfrac{3\times1}{2\times1}=\dfrac{3}{2}\)

bằng \(\frac{4831}{3960}\)

\(\frac{38}{48}-\left(\frac{8}{45}-\frac{17}{51}-\frac{3}{11}\right)\)

\(=\frac{38}{48}-\left(-\frac{212}{495}\right)\)

\(=\frac{4831}{3960}\)

1.

a, 2/3=12/x

12/18=12/x

=>x=18

Vậy x=18

b, 14/56=1/x

1/4=1/x

=>x=4 

Vậy x=4

c, 24/36=x/12

2/3=x/12

8/12=x/12

=>x=8

Vậy x =8

2

38/11+4/17-5/11-3/17

=(38/11-5/11)+(4/17-3/17)

=33/11+1/17

=3+1/17

=51/17+1/17

=52/17

3.

2/7 x =2/3

x=2/3:2/7

x=2/3x7/2

x=7/3

Vậy x=7/3

2/5:x=1/3

x=2/5:1/3

x=2/5x3

x=6/5

Vậy x= 6/5

K cho mình nha bạn !!!!!!!!!!!!^^

Tớ không hiểu.  Cậu giải đi

lấy máy tính làm là ra liền

\(\dfrac{38}{45}-\left(\dfrac{8}{45}-\dfrac{17}{51}-\dfrac{3}{11}\right)\)
\(=\dfrac{38}{45}-\dfrac{8}{45}+\dfrac{17}{51}+\dfrac{3}{11}\)
\(=\left(\dfrac{38}{45}-\dfrac{8}{45}\right)+\dfrac{1}{3}+\dfrac{3}{11}\)
\(=\dfrac{2}{3}+\dfrac{1}{3}+\dfrac{3}{11}\)
\(=\left(\dfrac{2}{3}+\dfrac{1}{3}\right)+\dfrac{3}{11}\)
\(=1+\dfrac{3}{11}\)
\(=\dfrac{11}{11}+\dfrac{3}{11}\)
\(=\dfrac{14}{11}\)

a =143

b = 2510

c 28 x 73 = 2044

cái câu c tính nhẩm chết liền

d [ 1700 - 340 +17 ] : 17 = 81

2 . Tìm x 

a 7 . [ x - 3 ] - 6 = 1

   7 . [ x - 3 ]   = 1+6

7 . [ x - 3 ]     = 7

     x - 3 = 7 : 7

x - 3 =1

x=3+1=4

b 

[x+5] .2:11=6

[x+5] x 2  = 6 x 11

[ x + 5 ] x 2 = 66

x+2=66:2

x+2=33

x=33-2=31

Bài 1 

a, \(45+98=143\)

b, \(2605-95=2510\)

c,\(28.73+28\)

\(=28.\left(73+1\right)\)

\(=28.74\)

\(=2072\)

d,\(\left[1700-340+17\right]:17\)

\(=1700:17-340:17+17:17\)

\(=100-20+1\)

\(=81\)

Bài 2 

a, \(7.\left(x-3\right)-6=1\)

\(\Leftrightarrow7.\left(x-3\right)=7\)

\(\Leftrightarrow x-3=1\)

\(\Leftrightarrow x=4\)

b, \(\left(x+2\right).2:11=6\)

\(\Leftrightarrow\left(x+2\right).2=66\)

\(\Leftrightarrow x+2=33\)

\(\Leftrightarrow x=31\)

Ta có:

=\(\dfrac{6x45x11x17}{15x12x34x33}\)

= \(\dfrac{6x15x3x11x17}{15x6x2x17x2x11x3}\)

= \(\dfrac{1}{2x2}\)

=\(\dfrac{1}{4}\)

Những chữ x ở trên là dấu nhân nhé

\(\frac{38}{11}+\frac{4}{17}-\frac{5}{11}-\frac{3}{17}\) 

\(=\frac{38}{11}-\frac{5}{11}+\frac{4}{17}-\frac{3}{17}\) 

\(=\frac{33}{11}+\frac{1}{17}\) 

\(=3+\frac{1}{17}\) 

\(=\frac{52}{17}\)

38/11+4/17-5/11-3/17

=(38/11-5/11)+(4/17-3/17)

=3+1/17

=51/17+1/17=52/17

\(\left(\frac{38}{11}-\frac{5}{11}\right)+\left(\frac{4}{17}-\frac{3}{17}\right)=\frac{33}{11}+\frac{1}{17}=3+\frac{1}{17}=\frac{52}{17}\)