\(A=\frac{15}{19}\left(\frac{17}{23}+\frac{19}{23}-\frac{13}{23}\right)=\frac{15}{19}\left(\frac{17+19-13}{23}\right)=\frac{15}{19}\cdot\frac{23}{23}=\frac{15}{19}.1=\frac{15}{19}\)

-119025 đó bn...^_^... k nha bn...thanks♥

\(\dfrac{15}{19}.\dfrac{24}{23}.\dfrac{-19}{15}.\dfrac{23}{24}=-1\)

\(\dfrac{15}{19}.\dfrac{24}{23}.-\dfrac{19}{15}.\dfrac{23}{24}=\left(-\dfrac{19}{15}.\dfrac{15}{19}\right).\left(\dfrac{24}{23}.\dfrac{23}{24}\right)=-1.1=-1\)

\(\dfrac{15}{19}\cdot\dfrac{24}{23}\cdot\dfrac{-19}{15}\cdot\dfrac{23}{24}\)

\(=\dfrac{15}{19}\cdot\dfrac{-19}{15}\cdot\dfrac{23}{24}\cdot\dfrac{24}{23}\)

\(=-1\cdot1=-1\)

Sửa đề: \(\dfrac{2}{17}+\dfrac{15}{23}+\dfrac{15}{17}+\dfrac{4}{19}+\dfrac{8}{23}\)

\(=\left(\dfrac{2}{17}+\dfrac{15}{17}\right)+\left(\dfrac{15}{23}+\dfrac{8}{23}\right)+\dfrac{4}{19}\)

\(=1+1+\dfrac{4}{19}\)

\(=2+\dfrac{4}{19}\)

\(=\dfrac{42}{19}\)

\(#Tmiamm\)

\(=\dfrac{8}{23}+\dfrac{3}{19}-\dfrac{15}{17}-\dfrac{2}{17}+\dfrac{15}{23}=\dfrac{3}{19}\)

\(\left(\dfrac{8}{23}+\dfrac{3}{19}-\dfrac{15}{17}\right)-\left(\dfrac{2}{17}-\dfrac{15}{23}\right)\\ =\dfrac{8}{23}+\dfrac{3}{19}-\dfrac{15}{17}-\dfrac{2}{17}+\dfrac{15}{23}\\ =\left(\dfrac{8}{23}+\dfrac{15}{23}\right)-\left(\dfrac{15}{17}+\dfrac{2}{17}\right)+\dfrac{3}{19}\\ =1-1+\dfrac{3}{19}\\ =\dfrac{3}{19}\)

ai tra loi di huhu

  Theo mình làm như vậy :

7/15 - 6/23 + 8/15 x 6/23 + 17/23

= ( 7/15 + 8/15 ) x ( 6/23 - 6/23 + 17/23 )

= 15/15             x            17/23

=     1               x             17/23

=              17/23.

Nếu như có gì sai sót , mong mọi người cho ý kiến chính xác nhất để mình có thể sửa chữa lại.

 -29.(85-47)-85.(47-29)

=-29.38-85.18

=-1102-1503

=-2605

-15.(23-29)+23-(15-29)

=-15.(-6)+23-(-14)

=90+23+14

=113+14

=127

 -13.(55-29)+23.(15-29)

=-13.26+23.(-14)

=-338+(-322)

=-660

-10.(2+4)-5.(4-3)

=-10.6-5.1

=-60-5

=-65

\(56.\left(15+23\right)-15.\left(23+56\right)\)

\(=\left(56.15+56.23\right)-\left(15.23+15.56\right)\)

\(=56.15+56.23-15.23-15.56\)

\(=\left(56.15-56.15\right)+\left(56.23-15.23\right)\)

\(=0.\left[23.\left(56-15\right)\right]\)

\(=23.41\)

\(=943\)

a)  56.[ 15 + 23 ] - 15.[ 23 + 56 ]

=   56. 38       -  15.  79

=      2128  -   1185

=           943

b)   12.[ 47 - 23 ]  +  23. [12 + 47]

 =    12 .  24        +   23.    59

 =         288         +       1357

=                   1645

~ chúc bạn hok tốt nha ~ ^_^

Đây là tính nhanh nha các bạn