/ là j v.

\(=\left(\dfrac{19}{42}+\dfrac{23}{42}\right)+\left(\dfrac{1}{37}+\dfrac{36}{37}\right)+10\)

=12

19 - 42 - 19 - 57 - 19

= ( 19 - 19 ) - ( 42 + 57 + 19 )

= 0 - 118

= -118

Revival

Kia là phép nhân mà, sao lại chuyển thành trừ đc?

   19 - 42.(-19) - 57.(-19)

= -19.(-1 - 42 - 57)

= -19 . (-100)

= 1900 

19 - 42 - 19 - 57 - 19

= -23 - 19 - 57 - 19

= -42 - 57 - 19

= -99 - 19

= -118

19 - 42(-19) - 57(-19) = 19 - ( 42 + 57 )(-19)

                                   = 19 - 99(-19)

                                   = 19 - (-1881) = 19 + 1881 = 1900

19 - 42(-19) - 57(-19)

= 19 - ( 42 + 57 )(-19)

 = 19 - 99(-19)

 = 19 - (-1881)

= 19 + 1881 = 1900

a) \(\dfrac{-25}{19}< \dfrac{-13}{19}< \dfrac{9}{19}< \dfrac{14}{19}< \dfrac{20}{19}< \dfrac{30}{19}< \dfrac{42}{19}\)

b) \(\dfrac{-2}{15}< \dfrac{-1}{10}< \dfrac{1}{6}< \dfrac{1}{5}< \dfrac{4}{15}< \dfrac{1}{3}< \dfrac{2}{5}\)

42(-19) + 19.(-58)

= (-42 - 58) . 19

= -100.19

= -1900

42 (-19)+19.(-58)

= (-42).19+19.(-58)

= 19[(-42)+(-58)]

= 19  .(-100)

=   -1900

ngoài ra còn cách này nữa

42.(-19)+19.(-58)

=42.(-19)+(-19).58

=(-19).(42+58)

=(-19).100

=-1900

1: \(=-26\cdot125+125\cdot36=125\cdot10=1250\)

b: \(=24\left(-125+225\right)=24\cdot100=2400\)

c: \(=42+58+19-19=100\)

a) \(\dfrac{25}{37}\times\dfrac{18}{29}+\dfrac{18}{29}\times\dfrac{12}{37}\)

\(=\dfrac{18}{29}\times\left(\dfrac{25}{37}+\dfrac{12}{37}\right)\)

\(=\dfrac{18}{29}\times\dfrac{37}{37}\)

\(=\dfrac{18}{29}\times1\)

\(=\dfrac{18}{29}\)

b) \(\dfrac{31}{85}\times\dfrac{11}{19}+\dfrac{31}{85}\times\dfrac{12}{19}-\dfrac{42}{19}\times\dfrac{31}{85}\)

\(=\dfrac{31}{85}\times\left(\dfrac{11}{19}+\dfrac{12}{19}-\dfrac{42}{19}\right)\)

\(=\dfrac{31}{85}\times\dfrac{-19}{19}\)

\(=\dfrac{31}{85}\times-1\)

\(=-\dfrac{31}{85}\)

c) \(\dfrac{16}{53}:\dfrac{17}{9}-\dfrac{16}{53}:\dfrac{17}{8}\)

\(=\dfrac{16}{53}:\left(\dfrac{9}{17}-\dfrac{8}{17}\right)\)

\(=\dfrac{16}{53}:\dfrac{1}{17}\)

\(=\dfrac{16}{901}\)

c) \(\dfrac{1}{5}\times\dfrac{12}{31}\times\dfrac{4}{3}+\dfrac{19}{31}\times\dfrac{4}{15}\)

\(=\dfrac{4}{15}\times\dfrac{12}{31}+\dfrac{19}{31}\times\dfrac{4}{15}\)

\(=\dfrac{4}{15}\times\left(\dfrac{12}{31}+\dfrac{19}{31}\right)\)

\(=\dfrac{4}{15}\times\dfrac{31}{31}\)

\(=\dfrac{4}{15}\times1\)

\(=\dfrac{4}{15}\)

a: =18/29*(25/37+12/37)

=18/29

b: =31/85(11/19+12/19-42/19)

=-31/85

c; =16/53(9/17+8/17)=16/53

d: =4/15(12/31+19/31)=4/15

\(=\dfrac{19}{33}.\left(\dfrac{4}{21}+\dfrac{25}{42}\right)\)

\(=\dfrac{19}{33}.\dfrac{33}{42}\)

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

Lời giải:
$=\frac{19}{33}\times (\frac{4}{21}+\frac{25}{42})$

$=\frac{19}{33}\times (\frac{8}{42}+\frac{25}{42})$

$=\frac{19}{33}\times \frac{33}{42}=\frac{19}{42}$