\(a.=\left(\dfrac{4}{5}.\dfrac{5}{6}\right).\dfrac{2}{3}=\dfrac{4}{6}.\dfrac{2}{3}=\dfrac{4}{9}\)

\(b.\dfrac{4}{5}.\dfrac{3}{4}+\dfrac{5}{4}.\dfrac{3}{4}=\dfrac{3}{5}+\dfrac{15}{16}=\dfrac{123}{80}\)

\(c.\left(\dfrac{11}{23}+\dfrac{9}{23}\right)+\left(\dfrac{2}{23}+\dfrac{18}{23}\right)=\dfrac{20}{23}+\dfrac{20}{23}=\dfrac{40}{23}\)

\(d.\left(\dfrac{27}{12}-\dfrac{25}{36}\right)+\left(\dfrac{17}{6}-\dfrac{15}{6}\right)=\dfrac{14}{9}+\dfrac{1}{3}=\dfrac{17}{9}\)

dấu chấm là gì vậy

dấu chấm là dấu x trong cấp trên

23 + 23 . 2 + 23 . 3 + 23 . 4

= 23 . 1 + 23. 2 + 23 . 3 + 23. 4

= 23 . (1 + 2 + 3 + 4)

= 23 . 10

= 230

23 + 23 . 2 + 23 . 3 + 23 . 4

= 23 . 1 + 23. 2 + 23 . 3 + 23. 4

= 23 . (1 + 2 + 3 + 4)

= 23 . 10

= 230

248 nhân 2005 - 2005 nhân 148

Giải:

17/13.18/23-4/13.18/23-(-5/23)

=18/23.(17/13-4/13)+5/23

=18/23.1+5/23

=18/23+5/23

=1

Chúc bạn học tốt!

TL: 

8/15 x 5/6 = 40/90 = 4/9 

41/20 x 3/4 = 123/80 

(11/23 + 9/23) + (18/23 + 2/23) = 20/23 + 20/23 = 40/43 

HT

\(\left(\frac{2}{3}\times\frac{4}{5}\right)\times\frac{5}{6}\) = \(\frac{2}{3}\times\frac{4}{5}\times\frac{5}{6}\)=\(\frac{2\times4\times5}{3\times5\times6}\)=\(\frac{2\times4\times5}{3\times5\times2\times3}\)=\(\frac{4}{9}\)

\(\frac{11}{23}+\frac{2}{23}+\frac{9}{23}+\frac{18}{23}\)=\(\frac{\left(11+9\right)+\left(18+2\right)}{23}\)=\(\frac{20+20}{23}\)=\(\frac{40}{23}\)

\(\frac{27}{12}+\frac{17}{6}-\frac{25}{36}-\frac{15}{6}\)=\(\left(\frac{27}{12}-\frac{25}{36}\right)+\left(\frac{17}{6}-\frac{15}{6}\right)\)=\(\frac{14}{9}+\frac{2}{6}\)=\(\frac{17}{9}\)

/HT\

Nhập các bạn toàn bắt tớ làm à ngu gò mà làm

23+23*2+23*3+23*4

=23*1+23*2+23*3+23*4

=23*(1+2+3+4)

=23*10

=230

23 + 23 x 2 + 23 x 3 + 23 x 4 

= 23 x ( 1 + 2 + 3 + 4 )

= 23 x 10

= 230

23+23x2+23x3+23x4

=23x(1+2+3+4)

=23x10

=230

k mik nha

\(=23\times\left(1+2+3+4\right)\\ =23\times10=230\)

= 23 x ( 1 + 2 + 3 + 4 )

= 23 x 10

= 230

 = 23 x4 + (2 + 4)

=92         + 6

= 98

Ta có: \(23\dfrac{1}{4}:\left(-\dfrac{3}{7}\right)-23\dfrac{1}{4}:\left(-\dfrac{5}{7}\right)\)

\(=\dfrac{93}{4}\cdot\dfrac{-7}{3}-\dfrac{93}{4}\cdot\dfrac{-7}{5}\)

\(=\dfrac{93}{4}\cdot\left(-\dfrac{7}{3}+\dfrac{7}{5}\right)\)

\(=\dfrac{93}{4}\cdot\dfrac{-14}{15}=-\dfrac{217}{10}\)