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2020 x 2021 - 3031 = 2020 x ( 2 + 2019 ) - 3031 = 2020 x 2019 + 2020 x 2 - 3031 = 2019 x 2020 + 1009
Nên ( 2019 x 2020 + 1009 ) : ( 2020 x 2021 - 3031 ) = ( 2019 x 2020 + 1009 ):( 2019 x 2020 + 1009 )=1
Ta có : \(\frac{\left(11,2-10-1,2\right)x\left(3,75-0,75\right)}{2011+3014}=\frac{0x3}{2011+3014}=\frac{0}{2011+3014}=0\)
\(\Rightarrow\left(2000\times7,5+2012:3\right)\times\left(21-3,5\times0,25\right)\times\frac{\left(11,2-10-1,2\right)\times\left(3,75-0,75\right)}{2011+3014}\)
\(=\left(2000\times7,5+2012:3\right)\times\left(21-3,5\times0,25\right)\times0\)
\(=0\)
= ( 1 + 3 + 5 + ... + 2011 ) - ( 2 + 6 + 8 + ... + 2010 )
= [ 1006 x ( 2011 + 1 ) : 2 ] - [ 1005 x ( 2010 + 2 ) : 2 ]
= ( 1006 x 2012 : 2 ) - ( 1005 x 2012 : 2 )
= ( 2024072 : 2 ) - ( 2022060 : 2 )
= 1012036 - 1011030
= 1006
Ta có:
\(\frac{2017}{2019}=1-\frac{2}{2019}\)
\(\frac{2018}{2020}=1-\frac{2}{2020}\)
Vì \(\frac{2}{2019}>\frac{2}{2020}\)
=> \(1-\frac{2}{2019}>1-\frac{2}{2020}\)
=> \(\frac{2017}{2019}>\frac{2018}{2020}\)
1
a.2008+2009+2010+2011+2012
=(2008+2012)+(2009+2011)+2010
=2020+2020+2010
=4040+2010
=6050
b.17,75+4,64+7,63+2,25
=(17,75+2,25)+(4,64+7,63)
=20+12,27
=32,27
c.7/9+2/3+2/9+1
=(7/9+2/9)+1+2/3
=1+1+2/3
=2+2/3
=5/3
2.
a.12,3x2,5+2,5x27,7
=2,5x(12,3+27,7)
=2,5x40
=100
b.42x3+42x12-42x5
=42x(3+12-5)
=42x10
=420
c.13,8-4,24-5,76+2,2
=(13,8-2,2)-(5,76+4,24)
=11,4-10
=1,4
3.
a.Xx3,1+Xx6,9=30,4
X x (3,1+6,9)=30,4
=X x10=30,4
X=30,4:10
X=3,04
b.X:1,5+0,45=7,65
X:1,5=7,65-0,45
X:1,5=7,2
X=7,2x1,5
X=10,8
1 tinh bang cach thuan tien nhat
a ( 2008 +2012 ) + (2009+2011) + 2010
= 2020+ 2020+2010
=2050
b (17,75 +2,25 ) + 7,63+2,25
= 21+7,63+2,25
=30,88
7/9+2/3+2/9 +1
= (2/9 +7/9 ) + 2/3+ 1
= 1+ 2/3 + 1
= 2 và 2/3
2
= 2,5 x ( 12,3 + 27,7 )
= 2,5 x 40
=16
42 x ( 3+12 -5 )
= 42 x 10
= 420
( 13,8 +2,2 ) - 4,24-5,76
= 16 - 4,24-5,76
= 5
3 tim x
X * 3,1 + x * 6,9 = 30,4
x = 30,4 : ( 3,1+6,9 )
x= 30,4 ; 10
x= 3,04
b x: 1,5 + 0,,45 = 7,65
x= 7,65 x ( 1,5 + 1.45 )
x= 7.65 x 2,95
x=22,5675
minh nhanh nhat nha
2009 x 3,68 + 3,68 - 3,38 x 1010
= 3,68 x (2009 + 1) - 3,38 x 1010
= 3,68 x 2010 - 3,38 x 1010
= (3,68 - 3,38) x (2010 - 1010)
= 0,3 x 1000
= 300
2009 x 3,68 + 3,38 - 3,38 x 1010
= 3,38 x ( 2009 + 1 ) - 3,38 x 1010
= 3,68 x 2010 - 3,38 x 1010
= ( 3,68 - 3,38 ) x ( 2010 - 1010 )
= 0,3 x 1000
= 300
=2010×2020−1010=1010×(2×2020−1)=1010×(4040−1)=1010×4039
=2011×1019−1019=1019×(2011−1)=1019×2010
B=1019×2010/1010×4039
B=1/2 x 4039/1019
B=1/2 x 4
B=2
Tick nhaa