5+5+5+5=20

5:5=1

5x1=5

k mik nha ban yêu minh  lai

5+5+5+5=20

5:5=1

5x1=5

ủng hộ mk nha

nhấn  cho mk nha 

`5/39xx(7 4/5xx1 2/3+8 1/3xx7 4/5)`

`=5/39xx(39/5xx5/3+25/3xx39/5)`

`=5/39xx39/5(5/3+25/3)`

`=1xx30/3`

`=10`

10

hổng hiểu gì hết

tui cũng vậy

\(\frac{7}{9}\times\frac{3}{5}+\frac{3}{5}\times\frac{5}{6}+\frac{3}{5}\times1\)

\(=\frac{3}{5}\times\left(\frac{7}{9}+\frac{5}{6}+1\right)\)

\(=\frac{3}{5}\times\frac{47}{18}\)

\(=\frac{47}{30}\)

 #hoktot<3# 

2/5 x 1/x + 1/x x 2 + 2/5 = 1/2

1/x x ( 2/5 + 2 ) + 2/5 = 1/2

1/x x 6/5 + 2/5 = 1/2

1/x x 6/5 = 1/2 - 2/3

( 1 : x) x 6/5 = -1/6

1:x = -1/6 : 6/5

1: x = -5/36

⇔ x =  -36/5.

Vậy x = -36/5.

\(\dfrac{4}{5}-\dfrac{2}{5}\times\dfrac{1}{4}=\dfrac{4}{5}-\dfrac{1}{10}=\dfrac{8}{10}-\dfrac{1}{10}=\dfrac{7}{10}\)

\(\dfrac{1}{4}+\dfrac{3}{4}:\dfrac{1}{8}=\dfrac{1}{4}+\dfrac{3}{4}\times8=\dfrac{1}{4}+6=\dfrac{1}{4}+\dfrac{24}{4}=\dfrac{25}{4}\)

\(\)\(\dfrac{11}{10}-\dfrac{2}{5}:\dfrac{1}{3}=\dfrac{11}{10}-\dfrac{2}{5}\times3=\dfrac{11}{10}-\dfrac{6}{5}=\dfrac{11}{10}-\dfrac{12}{10}=-\dfrac{1}{10}\)

4/5-2/5.1/4

=4/5-1/10

=8/10-1/10

=7/10

1/4+3/4:1/8

=1/4+3/4.8

=1/4+6

=1/4+24/4

=25/4

11/10-2/5:1/3

=11/10-2/5.3

=11/10-6/5

=11/10-12/10

=-1/10

Ta có :

5 x 0 = 0

Vì số nào nhân với 0 cũng bằng không

Đáp số 0

5x0=0

Vì số nào nhân với 0 cũng bằng 0

\(x-\dfrac{11}{15}=3+\dfrac{x}{5}\\ \Leftrightarrow\dfrac{4}{5}x=\dfrac{56}{15}\\ \Leftrightarrow x=\dfrac{14}{3}\)

\(\dfrac{2}{5}\times\dfrac{1}{x}+\dfrac{1}{x}\times2+\dfrac{2}{5}=\dfrac{1}{2}\\ \Leftrightarrow\dfrac{12}{5}\times\dfrac{1}{x}=\dfrac{1}{10}\\ \Leftrightarrow\dfrac{1}{x}=\dfrac{1}{24}\\ \Leftrightarrow x=24\)

tích đúng mình giải cho

= 1/1x2 + 1/2x3 + 1/3x4 + 1/4x5 + 1/5 x 6

= (1 - 1/2) + (1/2 - 1/3) + (1/3 - 1/4) + (1/4 - 1/5) + (1/5 - 1/6)

= 1 - 1/6

= 5/6

nha,mơn nhìu

a) \(\dfrac{2}{5}\cdot\dfrac{1}{7}+\dfrac{2}{5}\cdot\dfrac{5}{7}+\dfrac{2}{5}\)

\(=\dfrac{2}{5}\left(\dfrac{1}{7}+\dfrac{5}{7}+1\right)\)

\(=\dfrac{2}{5}\cdot\dfrac{13}{7}=\dfrac{26}{35}\)

b) \(\dfrac{1}{5}+\dfrac{2}{8}+\dfrac{4}{5}+\dfrac{7}{8}-\dfrac{1}{8}\)

\(=\left(\dfrac{1}{5}+\dfrac{4}{5}\right)+\left(\dfrac{2}{8}+\dfrac{7}{8}-\dfrac{1}{8}\right)\)

\(=1+1=2\)

c)\(\dfrac{24}{36}\cdot\dfrac{10}{12}\cdot36\)

\(=\dfrac{24\cdot10\cdot36}{36\cdot12}=\dfrac{12\cdot2\cdot10\cdot36}{12\cdot36}\)

\(=2\cdot10=20\)