a) 324-(112+324) = 324-112-324 = 0 -112 = (-112)

b) 53.(-15) + (-15)*47 = (-15)*(53+47) = (-15)*100 = -1500

c)43*(53-6) + 53*(-43) = 43*53 - 43*6 + 43*(-53)= 43*(53-53) - 43*6 = 0 - 258 = (-258)

d)(192 - 37 +85) - (85+192) = 192 -37 +85 -85 -192 = 0 -0 -37 = (-37)

10h18p ngày 1/5/2020

a) \(\dfrac{43}{47}=\dfrac{47-4}{47}=\dfrac{47}{47}-\dfrac{4}{47}=1-\dfrac{4}{47}\)

\(\dfrac{53}{57}=\dfrac{57-4}{57}=\dfrac{57}{57}-\dfrac{4}{57}=1-\dfrac{4}{57}\)

Vì \(\dfrac{4}{47}>\dfrac{4}{57}\)=>\(1-\dfrac{4}{47}< 1-\dfrac{4}{57}\)

=>\(\dfrac{43}{47}< \dfrac{53}{57}\)

b) Ta chọn phân số trung gian là: \(\dfrac{64}{81}\)

Vì \(\dfrac{64}{81}>\dfrac{64}{85}\)

Mà \(\dfrac{64}{81}< \dfrac{73}{81}\)

=> \(\dfrac{64}{85}< \dfrac{64}{81}< \dfrac{73}{81}\)

Vậy \(\dfrac{64}{85}< \dfrac{73}{81}\)

c) Ta chọn phân số trung gian là: \(\dfrac{18}{37}\)

Vì \(\dfrac{18}{37}>\dfrac{15}{37}\)

Mà \(\dfrac{18}{37}< \dfrac{18}{31}\)

=> \(\dfrac{15}{37}< \dfrac{18}{37}< \dfrac{18}{31}\)

Vậy \(\dfrac{18}{31}>\dfrac{15}{37}\)

Phần d) mình không biết lời giải

Mình chỉ biết \(\dfrac{12}{47}>\dfrac{19}{77}\) thôi !

\(\text{a) 43 (53 - 81) + 53 (81 - 43) }\)

\(=43.53-43.81+53.81-53.43\)

\(=53.\left(43-43\right)+81.\left(-43+53\right)\)

\(=53.0+81.10\)

\(=810\)

\(\text{ b) 4. (-5)2 + 2.(-5) - 20}\)

\(=\left(-20\right).2+2.\left(-5\right)-20\)

\(=2.\left[\left(-20\right)+\left(-5\right)\right]-20\)

\(=2.\left(-25\right)-20\)

\(=-50-20\)

\(=-70\)

\(\text{c) 27. (15 - 12) - 15. (27 - 12) }\)

\(=27.15-27.12-15.27+15.12\)

\(=15.\left(27-27\right)+12.\left(-17+15\right)\)

\(=15.0+12.\left(-2\right)\)

\(=-24\)

\(\text{ d) 53 + (-51) + (-53) + 49}\)

\(=53-51-53+49\)

\(=\left(53-53\right)+\left(-51+49\right)\)

\(=0+\left(-2\right)\)

\(=-2\)

chúc bạn học tốt

a, 53.(-15)+(-15).47

=(-15)(53+47)

=(-15).100

=-1500

b, 43.(53-81)+53.(81-43)

=43.(-28)+53.38

=810

c,(-5).8+53.(81-43)

=-45+53.38

=1969

d, ban tu giai nốt

a,-15 . (53+47)

 = -15 . 100

=-1500

b,43.53-43.81+53.81-43.53

=(43.53-43.53)+81.(-43+53)

= 0 + 81.10

=0+810

=810

c,-40+-8

=-48

d,3.16+(-10)-20

=48+(-10)-20

=38-20

=18

a) 53 . (-15) + (-15) . 47

= (53 + 47) . (-15)

= 100 . (-15) 

= -1500

b) 43 . (53 - 81) + 53 . (81 - 43)

= 43 . (-28) + 53 . 38

= -1204 + 2014

= 810

c) (-5) . 8 + (-2) . 3

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

= 20 . (-2) + (-2) . 3

= (20 + 3) . (-2)

= -46

d) 3 . (-4)² + 2 . (-5) - 20

=  3.16 + (-10) - 20

= 18

k cho tớ nha bn

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

a,=75-5*15-5*40+60

=75-75-60+60

=0+0

=0

b,=35-7*5-7*18

=35-35-126

=0-126

=-126

c,(cau c hinh nhu sai de)

d,=43*53-43*81+53*81-53*43-31

=(43*53-53*43)+81*(-43+53)-31

=0+81*10-31

=810-31

=779

a, (-72).(15 - 49) + 15.(-56 + 72)

= -72 . 15 + 72.49  - 15.56 + 15.72

= (-72.15 + 15.72) + (72.49  - 15.56)

= 3528 - 84

= 2688

1b, 1532 + (-186) + (-1432) + (-14) + 123

= (1532 - 1432) - (186 + 14) + 123

= 100 - 200 + 123

= 223 - 200

= 23 

43.(53 - 81) + 53.(81 - 43)

= 43.53 - 81.43 + 53.81 - 53.43

= (43.53 - 53.43) + (81.53 - 81.43)

= 0 + 81.(53-43)

= 81.10

= 810

\(43\left(53-81\right)+53\left(81-43\right)\)

\(=43.53-81+53.81-43\)

\(=81\left(53-43\right)\)

\(=81.10\)

\(=810\)

\(43\left(53-81\right)+53\left(81-43\right)\)

\(=43.53-43.81+53.81-53.43\)

\(=\left(43.53-53.43\right)+81\left(-43+53\right)\)

\(=0+81.10\)

\(=810\)

\(43\left(53-81\right)+53\left(81-43\right)\)

\(=43.53-81+53.81-43\)

\(=81\left(53-43\right)\)

\(=81.10\)

\(=810\)