Cach 1     \(\frac{3}{4}\times\frac{1}{2}\times2\)

= \(\frac{3}{4}\times\frac{1}{2}\times\frac{2}{1}\)

= \(\frac{3\times1\times2}{4\times2\times1}\)

= \(\frac{6}{8}\)

= \(\frac{3}{4}\)

Cach 2     \(\frac{3}{4}\times\frac{1}{2}\times2\)

= \(\frac{3}{4}\times\frac{1}{2}\times\frac{2}{1}\)

= \(\frac{3\times1\times2}{4\times2\times1}\)

=\(\frac{3}{4}\)

Đoạn này cần gach nhưng ở đây ko có gạch chéo nên bạn cố gắng hiểu nhé!

Chúc bạn học giỏi 

Nhớ cho mình 1 k đúng nhé!

3/4 x 1/2 x 2

C1 : = 3/8 x 2 

= 6/8

= 3/4

C2 : = 3/4 x 2/2

= 3/4 x 1

= 3/4

3/4x1/2x2=3/4x(1/2x2)=3/4x1=3/4

3/4x1/2x2=3/4x2x1/2=3/2x1/2=3/4

hok ............

1/2 + 1/3 + 1/4 + 1/5 + 4/5 + 3/4 + 2/3 + 1/2

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

= 1 + 1 + 1 + 1

= 4

\(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{4}{5}+\dfrac{3}{4}+\dfrac{2}{3}+\dfrac{1}{2}\)

\(=\left(\dfrac{1}{2}+\dfrac{1}{2}\right)+\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\left(\dfrac{1}{4}+\dfrac{3}{4}\right)+\left(\dfrac{1}{5}+\dfrac{4}{5}\right)\)

=1+1+1+1

=4

=(12+12)+(13+23)+(14+34)+(15+45)=(12+12)+(13+23)+(14+34)+(15+45)
=(12+12)+(13+23)+(14+34)+(15+45)

=1+1+1+1

=4

    25 x 8 x 50 x 125 x 4 x 2 

= ( 25 x 4 ) x ( 8 x 125 ) x ( 50 x 2 )

=    100      x     1000     x      100

=           100 000          x         100

=                        10 000 000

= ( 25 x 4 ) x ( 8 x 125 ) x ( 50 x 2 )

=    100      x     1000     x      100

=           100 000          x         100

=                        10 000 000

\(=1995\times1994-\dfrac{1}{\left(1994-1\right)}\times1995+1994\)

\(=1995\times1994-\dfrac{1}{1994}\times1995-1995+1994\)

\(=1995\times1994-\dfrac{1}{1994}\times1995-1\)

\(=1\)

\(\dfrac{1}{5}+\dfrac{4}{11}+\dfrac{4}{5}+\dfrac{7}{11}=\left(\dfrac{1}{5}+\dfrac{4}{5}\right)+\left(\dfrac{4}{11}+\dfrac{7}{11}\right)=\dfrac{5}{5}+\dfrac{11}{11}=1+1=2\)

\(\dfrac{5}{6}+\dfrac{8}{24}+\dfrac{1}{6}+\dfrac{16}{24}=\dfrac{5}{6}+\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{2}{3}=\left(\dfrac{5}{6}+\dfrac{1}{6}\right)+\left(\dfrac{1}{3}+\dfrac{2}{3}\right)=\dfrac{6}{6}+\dfrac{3}{3}=1+1=2\)

( 1/5+4/5)+ (4/11+7/11)

= 1+1=2

( 5/6+1/6)+ (8/24+16/24)

=1+1=2

a)\(=\left(\dfrac{1}{5}+\dfrac{4}{5}\right)+\left(\dfrac{4}{11}+\dfrac{7}{11}\right)=1+1=2\)

b)\(=\left(\dfrac{5}{6}+\dfrac{1}{6}\right)+\left(\dfrac{8}{24}+\dfrac{16}{24}\right)=1+1=2\)

Ta có : 147 . 25 + 147 . 74 + 174

= 147 . 25 + 147 . 74 + 147 + 27

= 147 . ( 25 + 74 + 1 ) + 27

= 147 . 100 + 27

= 14700 + 27 = 14727

Tớ nghĩ đề bài là: \(147.25+147.74+147\)

\(=147.\left(25+74\right)+147\)

\(=147.99+147\)

\(=147.\left(99+1\right)\)

\(=147.100\)

\(=14700\)

147x25+147x74+174

=147x(25+74)+174

=147x99+174

=14553+174

=14727

em kiểm tra lại đề nhé

\(\frac{1}{7}+\frac{2}{7}+\frac{3}{7}+\frac{4}{7}+\frac{5}{7}+\frac{6}{7}\)

\(=\left(\frac{1}{7}+\frac{6}{7}\right)+\left(\frac{2}{7}+\frac{5}{7}\right)+\left(\frac{3}{7}+\frac{4}{7}\right)\)

\(=1+1+1=3\)

\(\frac{1}{4}\times45+0,25\times35+\frac{25}{100}\times19+25\%\)

\(=0,25\times45+0,25\times35+0,25\times19+0,25\)

\(=0,25\times\left(45+35+19+1\right)\)

\(=0,25\times100=25\)

147 x 36 + 147 x 64

= 147 x ( 36 + 64 )

= 147 x 100 

= 14700

(36+64)x147x147=100x147x147

                             =2160900

  Lấy 1 số cộng với số nào đó thành mấy chục là tính cách thuận tiện nha

  147 x 36 + 147 x 64 

=  147 x ( 36 + 64 ) 

 =  147 x 100 

 =  14 700 

 nhớ nha bạn !