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(-28). 75 + (-25). 28
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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) 11 + 28 + 24 + 16 + 112 + 9
= ( 11 + 9 ) + ( 28 + 112 ) + ( 24 + 16 )
= 20 + 140 + 40
= 200
b) 75 - 13 - 17 - 25
= ( 75 - 25 ) - 13 - 17
= 50 - 13 - 17
= 20
A, 2 x 26 x 5 =( 5 x 2) x 26
10 x 26
=260
b,4 x 37 x 25 =( 4 x 25) x 26
= 100 x 26
= 3700
c, 25 x 5 x 4 x 27 x 2 =( 25 x 4 ) x ( 2x 5) x 27
= 100 x 10 x 27
= 1000x 27
=27000
d,28 x 64 + 28 x 36 = 28 x ( 64 + 36 )
= 28 x 100
=2800
e, 769 x 85 - 769 x 75 = 769 x ( 85 - 75 )
=769 x 10
=7690
f, 56 x 37 + 56 x 63 = 56 x ( 37 + 63 )
= 56 x 100
=5600
a. = 26 x (2 x 5)
= 26 x 10 =260
b.=( 25x4) x37
=100 x37=3700
c.=(25x4) x(5x2) x27
=100 x10 x27
= 27000
d.=28 x( 64+36)
=28 x100
= 2800
e.=769 x( 85-75)
=769 x10 =7690
f. =56 x(37 +63)
=56 x100
= 5600
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) \(\left(-456\right)-\left(67-456\right)\)
\(=-456-67+456\)
\(=\left(456-456\right)-67\)
\(=67\)
58 x 75 + 25 x 58 - 58 x 28
= 58 x ( 75 + 25 + 28 )
= 58 x 128
= 7424
58 x 75 + 25 x 58 - 58 x 28
= 58 x (75 + 25 - 28)
= 58 x 72
= 4176
27/18 - 9/15 = 405/270 - 162/270 = 243/270
14/28 - 25/75 = 1050/2100 - 700/2100 = 6
:0
m Fe2O3=28.\(\dfrac{75}{100}\)=21g =>n Fe2O3=\(\dfrac{21}{160}\)=0,13125 mol
m CuO=28-21=7 g =>n CuO=\(\dfrac{7}{80}\)=0,0875 mol
Fe2O3+3H2->2Fe+3H2O
0,13125-0,39375-0,2625
CuO+H2-to>Cu+H2O
0,0875-0,0875-0,0875 mol
=>m Fe=0,2625.56=14,7g
=>m Cu=0,0875.64=5,6g
=>n H2=0,39375+0,0875=0,48125mol
\(\left(-28\right).75+\left(-25\right).28\\ =-28.75-25.28\\ =28.25\left(-3-1\right)\\ =28.25.\left(-4\right)\\ =28.\left(-100\right)\\ =-2800\)
( -28) . 75+ ( -25) . 28
= 28 . (-75) + ( -25) .28
=28 . [ -75 + (-25) ]
= 28. ( -100)
= -2800