giúp mik zứi😭😭😭

a; 60 \(\times\) (\(\dfrac{7}{12}\) + \(\dfrac{4}{15}\)) 

 =  60 \(\times\) \(\dfrac{7}{12}\) + 60 \(\times\) \(\dfrac{4}{15}\)

= 35 + 16

= 51

b; \(\dfrac{1}{2}\) \(\times\)\(\dfrac{2}{3}\) \(\times\) \(\dfrac{3}{4}\) \(\times\) \(\dfrac{4}{5}\) \(\times\) \(\dfrac{5}{6}\) \(\times\) \(\dfrac{7}{8}\) \(\times\) \(\dfrac{8}{9}\)

= \(\dfrac{2\times3\times4\times5\times6\times7\times8}{2\times3\times4\times5\times6\times7\times8}\) \(\times\) \(\dfrac{1}{9}\)

= 1 \(\times\) \(\dfrac{1}{9}\)

= \(\dfrac{1}{9}\)

\(\frac{4}{5}x\frac{1}{4}+\frac{1}{2}x\frac{4}{5}\)

\(\frac{4}{5}x\left(\frac{1}{4}+\frac{1}{2}\right)\)

\(\frac{4}{5}x\frac{3}{4}=\frac{3}{5}\)

\(\frac{3}{4}x\frac{4}{5}+\frac{5}{6}x\frac{6}{7}x\frac{7}{8}\)

\(\frac{3}{5}+\frac{5}{8}=\frac{49}{40}\)

A) 4/5 x 1/4 + 1/2 x 4/5

 = 4/5 x (1/4 + 1/2)

 = 4/5 x (1/4 + 2/4)

 = 4/5 x 3/4

 = 3/5

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

1,

a,=4/7:4/9.3

=9/7.3

=27/7

b,=(7/11+4/11).5/6

=1.5/6

=5/6

`(6/7-2/7):4/9xx3=4/7xx9/4xx3=[4xx9xx3]/[7xx4]=27/7`

`7/11xx5/6+4/11xx5/6=(7/11+4/11)xx5/6=11/11xx5/6=5/6`

Giải đấy đủ giúp mình với 

a: =8/15x1/4=2/15

b: \(=\dfrac{5}{3}\cdot\dfrac{4}{5}\cdot\dfrac{6}{7}=\dfrac{24}{21}=\dfrac{8}{7}\)

c: \(=\dfrac{2}{5}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)=\dfrac{2}{5}\)

trả lời mình đi

Tao mách cô mày hỏi bài thi nhá

`1/2 xx 2/3 xx 3/4 xx 4/5 xx 5/6 xx 6/7 xx 7/8 x 8/9`

`= [1 xx 2 xx 3 xx 4 xx 5 xx 6 xx 7 xx 8]/[2 xx 3 xx 4 xx 5 xx 6 xx 7 xx 8 xx 9]`

`= 1/9`

HT~

       4/3 x 5/4 x 6/5 x 7/6 x  8/7 x 9/8 

   =  4/9   

9/5 + 4/7 + 6/5 + 3/7

=  ( 9/5 + 6/5 ) + ( 4/7 + 3/7)

=            3        + 1

=        4

9/5 + 4/7 + 6/5 + 3/7 = (9/5 + 6/5) + (4/7 + 3/7)

= 15/5 + 7/7

= 3 + 1

= 4

1/2 x 45/33 x 1/9 x 11/6 = (1/2 x 1/9) x (45/33 x 11/6)

= 1/18 x 45/18

= 5/2

1/2 x 45/33 x 1/9 x 11/6

= (1/2 x 1/9) x (45/33 x 11/6)

= 1/18 x 45/18

= 5/2

\(\frac{3}{4}\times\frac{6}{7}-\frac{1}{4}\times\frac{6}{7}\)
\(=\left(\frac{3}{4}-\frac{1}{4}\right)\times\frac{6}{7}\)
\(=\frac{1}{2}\times\frac{6}{7}=\frac{3}{7}\)

\(\frac{3}{4}\cdot\frac{6}{7}-\frac{1}{4}\cdot\frac{6}{7}\)

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

\(=\frac{6}{7}\cdot1=\frac{6}{7}\)

lớp 4 chắc chưa biết nhỉ: dấu chấm là dấu nhân nha!

3/4 x 6/7 - 1/4 x 6/7

= ( 3/4 - 1/4 ) x 6/7

= 2/4 x 6/7

= 12/28