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

Phương pháp giải:

- Tính giá trị của mỗi vế

- So sánh rồi điền dấu thích hợp vào chỗ trống. 

Lời giải chi tiết:

19 + 7 < 19 + 9            17 + 7 < 17 + 9

17 + 9 = 19 + 7            37 + 15 < 55 − 1

38 − 8 = 23 + 7            28 − 3 > 17 + 6

Dể quá

A = 1

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tk mình nhé

Chúc bạn học giỏi

\(A=\frac{23}{17}-\frac{15}{19}+\frac{15}{19}-\frac{6}{17}\)

\(A=\left(\frac{23}{17}-\frac{6}{17}\right)+\left(\frac{15}{19}-\frac{15}{19}\right)\)

\(A=1+0\)

\(A=1\)

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bằng 1 nha

Tính nhanh (hợp lí) nha

\(A=\frac{-2}{17}+\frac{15}{23}+\frac{-15}{17}+\frac{4}{19}+\frac{8}{23}\)

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

\(=\frac{-17}{17}+\frac{23}{23}+\frac{4}{9}\)

\(=-1+1+\frac{4}{9}=0+\frac{4}{9}=\frac{4}{9}\)

                       #Hoq chắc _ Baccanngon

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

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

Bạn lấy mẫu chung

A=15/19 .17/29+15/29.19/23-15/19.13/23

A=15/19 (17/29 + 19/23 - 13/23)

A=15/19 . 1

A=15/19     

f)\(-\dfrac{2}{17}+\dfrac{15}{23}+-\dfrac{15}{17}+\dfrac{4}{19}+\dfrac{8}{23}\)
\(=\left(-\dfrac{2}{17}+-\dfrac{15}{17}\right)+\left(\dfrac{15}{23}+\dfrac{8}{23}\right)+\dfrac{4}{19}\)
\(=-1+1+\dfrac{4}{19}\)
\(=0+\dfrac{4}{19}=\dfrac{4}{19}\)
g)\(-\dfrac{1}{2}+\dfrac{3}{21}+-\dfrac{2}{6}+-\dfrac{5}{30}\)
\(=-\dfrac{1}{2}+\dfrac{1}{7}+-\dfrac{1}{3}+-\dfrac{1}{6}\)
\(=\left(-\dfrac{1}{2}+-\dfrac{1}{3}+-\dfrac{1}{6}\right)+\dfrac{1}{7}\)
\(=-\dfrac{3+2+1}{6}+\dfrac{1}{7}\)
\(=\dfrac{1}{7}-1\)
\(=\dfrac{1}{7}-\dfrac{7}{7}=-\dfrac{6}{7}\)

`f)(-2)/17 + 15/23 + (-15)/17 + 4/19 + 8/23`

`= (-2/17+ -15/17)+(15/23+8/23)+4/19`

`= -1+1+4/19`

`= 0 +4/19`

`= 0`

`g)(-1)/2 + 3/21 + (-2)/6 + (-5)/30`

`= (-1)/2 + 1/7 + (-1)/3 + (-1)/6`

`= (-21)/42 + 6/42 + (-14)/42 + (-7)/42`

`=(-36)/42`

`=(-6)/7`

\(f,-\dfrac{2}{17}+\dfrac{15}{23}-\dfrac{15}{17}+\dfrac{4}{19}+\dfrac{8}{23}\)

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

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

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

\(g,-\dfrac{1}{2}+\dfrac{3}{21}-\dfrac{2}{6}-\dfrac{5}{30}\)

\(=-\dfrac{5}{14}-\dfrac{1}{2}\)

\(=-\dfrac{5}{14}-\dfrac{7}{14}\)

\(=-\dfrac{6}{7}\)