\(=\dfrac{3}{4}\cdot\dfrac{5}{7}\cdot\dfrac{14}{15}=\dfrac{3}{15}\cdot\dfrac{5}{4}\cdot\dfrac{14}{7}=2\cdot\dfrac{1}{5}\cdot\dfrac{5}{4}=2\cdot\dfrac{1}{4}=\dfrac{1}{2}\)

trả lời giúp mình với ạ :(

`3/4 xx 5/7 xx14/15`

`=(3xx5)/(4xx7) xx 14/15`

`= 15/28 xx 14/15`

`=(15xx14)/(28xx15)`

`=14/28`

`=1/2`

A=(15x4)x7

A=60x7

A=420

đúng cho 1k

420nha bạn

chúc hok giỏi

Tính nhanh :

A = 15 x 7 x 4

A =  ( 15 x 4 ) x 7

A =     60 x 7

A =      420

A)4/5x (5/6+1/6)

   4/5x     1= 4/5

\(a,\dfrac{5}{6}\times\dfrac{4}{5}+\dfrac{4}{5}\times\dfrac{1}{6}+\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{5}{6}+\dfrac{1}{6}+1\right)=\dfrac{4}{5}\times2=\dfrac{8}{5}\)

\(b,60\times\left(\dfrac{105}{180}+\dfrac{48}{180}\right)=60\times\dfrac{17}{20}=51\)

a) \(\dfrac{5}{6}\times\dfrac{4}{5}+\dfrac{4}{5}\times\dfrac{1}{6}+\dfrac{4}{5}\)

\(=\dfrac{5}{6}\times\dfrac{4}{5}+\dfrac{4}{5}\times\dfrac{1}{6}+\dfrac{4}{5}\times1\)

\(=\dfrac{4}{5}\times\left(\dfrac{5}{6}+\dfrac{1}{6}+1\right)\)

\(=\dfrac{4}{5}\times2\)

\(=\dfrac{8}{5}\)

b) \(60\times\left(\dfrac{7}{12}+\dfrac{4}{15}\right)\)

\(=60\times\dfrac{17}{20}\)

\(=\dfrac{1020}{20}\)

\(=51\)

15 x 25 x 7 x 4 + 170 x 160

= (25 x 4) x (15 x 7) + 170 x 160

= 100 x 105 + 27200

= 10500 + 27200

= 37700

15 x 25 x 7 x 4 + 170 x 160

= ( 25 x 4 ) x ( 15 x 7 ) + 27200

= 100 x 105 + 27200

= 10500 + 27200

= 37700

Tk nha!!

\(15\times25\times7\times4+170\times160\)

\(=\left(25\times4\right)\times\left(15\times7\right)+170\times160\)

\(=100\times105+170\times160\)

\(=10500+27200\)

\(=37700\)

Mn giúp mh với đg cần gấp lắm ln🥺🥺

\(1,\frac{2}{3}+\frac{4}{9}+\frac{1}{5}+\frac{2}{15}+\frac{3}{2}-\frac{17}{18}\)

\(< =>\frac{4}{9}+\frac{3}{2}+\left(\frac{2}{3}+\frac{1}{5}+\frac{2}{15}\right)-\frac{17}{18}\)

\(< =>\frac{8}{18}+\frac{27}{18}+\left(\frac{10}{15}+\frac{3}{15}+\frac{2}{15}\right)-\frac{17}{18}\)

\(< =>\frac{35}{18}+1-\frac{17}{18}\)

\(< =>\frac{53}{18}-\frac{17}{18}\)

\(< =>2\)

\(2,\frac{13}{28}\cdot\frac{5}{12}-\frac{5}{28}\cdot\frac{1}{12}\)

\(< =>\left(\frac{13}{28}-\frac{5}{28}\right)\cdot\left(\frac{5}{12}-\frac{1}{12}\right)\)

\(< =>\frac{2}{7}\cdot\frac{1}{3}\)

\(< =>\frac{2}{21}\)

\(3,\frac{19}{4}\cdot\frac{15}{23}-\frac{15}{4}\cdot\frac{7}{23}+\frac{15}{4}\cdot\frac{11}{23}\)

\(< =>\frac{285}{92}-\frac{105}{92}+\frac{165}{92}\)

\(< =>\frac{15}{4}\)

cảm ơn bạn nha bạn chắc chăn đúng không

bạn viết dấu gạch ngang của phân số như thế nào đấy nguyen thi hien

7/4 x 15/7 + 13/7 x 9/4 - 7/4 x2/7

=7/4 x 15/7- 7/4 x2/7+ 13/7 x 9/4

=7/4 x (15/7 - 2/7) + 13/7 x 9/4

=7/4 x 13 /7 + 13/7 x 9/4

=13/7 x (7/4+9/4)

=13/7 x 16/4

=13/7 x 4

=52/7

k mk nha

sorry câu trả lời vừa nãy mk ấn nhầm

7/4 x 15/7 + 13/7 x 9/4 - 7/4 x2/7

=7/4 x 15/7 - 7/4 x 2/7 + 13/7 x 9/4

a) chứng tỏ : abcabc chia hết cho 11

Ta có 123123:11=11193

Vậy abcabc chia hết cho 11

b)\(\frac{9\cdot15\cdot21\cdot12\cdot20}{5\cdot6\cdot45\cdot18\cdot4}=\frac{9\cdot3\cdot5\cdot3\cdot7\cdot2\cdot2\cdot3\cdot2\cdot2\cdot5}{5\cdot2\cdot3\cdot5\cdot3\cdot3\cdot2\cdot3\cdot3\cdot2\cdot2}\)\(=\frac{7\cdot5}{3}=\frac{35}{3}\)