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A)
-65.(87-17)-87.(17-65)
=-65.87-(-65).17-87.17-87.(-65)
=-(-65).17-87.17
=65.17-87.17
=17.(65-87)
=17.(-22)
=-374
B)
72.(28-49)+28.(-49-72)
= 72.28-72.49+28.(-49)-28.72
= -72.49+28.(-49)
= 72.(-49)+28.(-49)
= (-49).(72+28)
= -49.100
=-4900
C)
18-(-27)+63-(63+27)
= 18+27+63-63-27
= 45+0-27
= 45+(-27)
=45-27
=18
KICK MÌNH NHÁ
72.(28 - 49) + 28.(-49 - 72)
= 72.28 - 72.49 + 28.(-49) - 28.72
= (72.28 - 28.72) - [72.49 - 28.(-49)
= 0 - [(-72)(-49) - 28.(-49)]
= 0 - [(-49).(-72 - 28)]
= 0 - [(-49).(-100)]
= 0 - 4900
= -4900
72.(28-49)+28.(-49-72)=72.28-72.49+28.(-49)-28.72
=72.28-28.72+28.(-49)-(-72).49
=72.28-28.72+28.(-49)-(-49).72
=72.(28-28)+(-49).(28+72)
=0+(-49).100
=-4900
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 ) 5 . ( - 2 ) . ( - 3 )
= ( - 10 ) . ( - 3 )
= 30
b ) ( - 20 ) + ( - 12 ) - ( - 4 )
= ( - 20 ) + ( - 12 ) + 4
= ( -20 ) + [ ( - 12 ) + 4 ]
= ( - 20 ) + ( - 8 )
= - 28
c . 78 . 45 - 145 . 78
= 78 . ( 45 - 145 )
= 78 . ( - 100 )
= - 7800
a, [ 13-17 ].[-10]+[-7]0
=-4.[-10]+1
=40+1
=41
b, 72.[28-49] + 28.[-49-72]
=72.[-21]+28.[-121]
=-1512+[-3388]
=-4900
c, -65.[87-17] - 87.[17-65]
=-65.70-87.[-48]
=4550-[-4276]
=8726
d, -23.63+23.21-58.23
=23.(-63)+23.21-58.23
=23.(-63+23-58)
=23.(-40-58)
=23.(-98)
=-2254
e, 25.134+25.[-34]
=25.[134+(-34)]
=25.100
=2500
1: Ta có: \(2155-\left(174+2155\right)+\left(-68+174\right)\)
\(=2155-174-2155-68+174\)
=-68
2) Ta có: \(-25\cdot72+25\cdot21-49\cdot25\)
\(=-25\cdot\left(72-21+49\right)\)
\(=-25\cdot100=-2500\)
a)BCNN(72,540)=1080
b)BCNN(28,49,64)=3136
c)BCNN(43,53)=2279
a) \(\left(-25\right).5.\left(-4\right).2\)
\(=\left[\left(-25\right).\left(-4\right)\right].\left(2.5\right)\)
\(=100.10=1000\)
b) \(\left(-456\right)-\left(67-456\right)\)
\(=-456-67+456\)
\(=\left(456-456\right)-67\)
\(=67\)
72x(28-49)+28x(-49-72)
=72x(-21)+28x(-121)
=-1512+(-3388)
=-49900
Có 2 cách hiểu
+ ) 72x( 28 - 49 ) + 28x( -49 - 72)
= 72x . 28 - 72x . 49 - 28x . 49 - 28x . 72
= -72x . 49 - 28x . 49
= 49 . ( - 100x )
+) 72 . ( 28 - 49 ) + 28 . ( -49 - 72 )
= 72 . 28 - 72 . 49 -28 . 49 - 28 . 72
= -72 . 49 -28 . 49
= 49 . ( -100 ) = -4900
= 72 . 28 -72. 49 + 28. (-49)-28.72
= 72.28 - 28 . 72 - 72 . 49 + 28 . (-49)
= 0 - 72 . 49 + 28 . ( -49 )
= -72 .49 + 28 . ( -49)
= 72 . ( -49) + 28 . (-49)
= (72+28) .(-49)
= 100 . (-49)
= -4900
k mình nha !
-4900