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a. ( - 57 ) . ( 67 - 34 ) - 67 . (34 -57 )
= - 57 . 67 - ( - 57 ) . 34 - 67 . 34 - 67 . 57
= 57 . ( 67 - 67 ) + 34 . ( 67 - 57 )
= 57 . 0 + 34 . 10
= 0 + 340
= 340
45-58+(-45)+(+58)-3=45-58-45+58-3=(45-45)+(58-58)-3=-3
(-57)-(-12)+3-(-57)=-57+12+3+57=(-57+57)+12+3=15
-(-24)-(-30)+(-24)-30+8=24+30-24-30+8=(24-24)+(30-30)+8=8
-(-12)+(+19)-(+12)+8-19=12+19-12+8-19=(12-12)+(19-19)+8=8
47-(-53)+(-47)-(+53)=47+53-47-53=(47-47)+(53-53)=0
-(+28)+32-(-28)+(-34)=-28+32+28-34=(-28+28)-(34-32)=-2
15-(+72)+(-15)+(+72)=15-72-15+72=(15-15)+(72-72)=0
20-(+46)+(-25)-(-46)=20-46-25+46=(20-25)+(46-46)=-5
28-(-32)+(-28)-32+5=28+32-28-32+5=(28-28)+(32-32)+5=5
-75+(-49)+(+75)+49-12=-75-49+75+49-12=(-75+75)+(49-49)-12=-12
\(...=45-58-45+58-3=-3\)
\(...=-57+12+3+57=15\)
\(...=24+30-24-30+8=8\)
\(...=12+19-12+8-19=8\)
\(...=47+53-47-53=0\)
\(...=-28+32+28-34=-2\)
\(...=15-72-15+72=0\)
\(...=20-46-25+46=-5\)
\(=...28+32-28-32+5=5\)
\(...=-75-49+75+49-12=-12\)
a/ 25 x ( 32 + 47 ) - 32 x ( 25 + 47 )
= 25 x 79 - 32 x 72
= 1975 - 2304
= -329
b/ 48 x ( 21- 19 ) - 21 x ( 48 - 19 ) + 27 x ( -81 )
= 48 x 2 - 21 x 29 + 27 x ( -81 )
= 96 - 609 + -2187
= -2700
cau co phai vu phuong huyen ko.Neu phai thi cau hay vao ket ban voi to
\(P=\dfrac{32}{64}\cdot\dfrac{-57}{19}+\dfrac{35}{21}\cdot\dfrac{22}{44}=\dfrac{1}{2}\left(-3+\dfrac{5}{3}\right)=\dfrac{1}{2}\cdot\dfrac{-4}{3}=\dfrac{-2}{3}\)
\(Q=\dfrac{75}{125}\cdot\dfrac{82}{164}+\dfrac{49}{98}\cdot\dfrac{-35}{105}=\dfrac{1}{2}\left(\dfrac{3}{5}-\dfrac{1}{3}\right)=\dfrac{1}{2}\cdot\dfrac{4}{15}=\dfrac{2}{15}\)
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 \(\dfrac{18}{31}>\dfrac{15}{37}\)
a, 119 + 24 + 81
= ( 119 + 81 ) + 24
= 200 + 24
= 224
b, 16 . 6 . 125
= 16 . 125 . 6
= 2000 . 6
= 12000
c, 25 . 104
= 25 . 100 + 25 . 4
= 2500 + 100
= 2600
d, 12 . 19 + 12
= 12 . 19 + 12 . 1
= 12 . ( 19 + 1 )
= 12 x 20
= 240
e, 43 . 27 + 93 . 43 + 57 . 61 + 59 . 57
= 43 . ( 27 + 93 ) + ( 61 + 59 ) . 57
= 43 . 120 + 120 . 57
= 120 . 43 + 120 . 57
= 120 . ( 43 + 57 )
= 120 . 100
= 12000
a/ 199 + 24 + 81
= (119+81) + 24
= 200 + 24
= 224
b/ 16 . 6 . 125
= ( 16 . 125) . 6
= 2000 . 6
= 12000
c/ 25 . 104
= 25 . ( 100 + 4 )
= 25 . 100 + 25 . 4
= 2500 + 100
= 2600
d/43 . 27 + 93 . 43 + 57 . 61 + 59 . 57
= 43 . ( 27 + 93) + 57 . ( 61+ 59)
= 43 . 130 + 57 . 130
= (43 + 57) . 130
= 100 . 130
= 1300
A. -21 + 57 - (-195) + 43 - 93
=36+195+43-93
=274-93
=181
B. -25 . 19 - 19 . (-125) + (-310)
=-475-19.(-125)-310
=-475-2375-310
=-3160
C. 64 . 47 . 32 . 106 - (-54)
=3008.3392+54
=10203136+54
=10203190