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1999 x 2011 - 1999
=1999 x 2011 -1999 x 1
=1999x(2011-1)
=1999 x 2010
= 4017990
2010 x 1998 - 2010
=2010 x 1998 -2010 x 1
= 2010 x ( 1998 -1 )
= 2010 x 1997
= 4013970
a)1999 x 2011 - 1999
= 4019989 - 1999
= 4017990
b)2010 x 1998 - 2010
= 4015980 - 2010
= 4013970
Mong bạn k mik
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\(\dfrac{2012x2010+2011}{2010x2013+1}=\dfrac{4044120+2011}{4046130+1}=\dfrac{4046131}{4046131}\)\(=1\)
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a)(3/2-0,5)/x=7/2+1/4
(3/2-1/2)/x=14/4+1/4
1/x=15/4
x=1:15/4
x=4/15
b)(x*0,25+2010)*2011=(53+2010)*(2012-1)
(x*0,25+2010)*2011=2063*2011
=>0,25x+2010=2063
0,25x=2063-2010
0,25x=53
x=53/0,25
x=212
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a. 1⋅2⋅3+2⋅4⋅6+3⋅6⋅9+4⋅8⋅12
= 6+2⋅4⋅6+3⋅6⋅9+4⋅8⋅12
= 6+48+3⋅6⋅9+4⋅8⋅12
= 6+48+162+4⋅8⋅12
= 6+48+162+384
= 600
b . Ta có \(A=\frac{2010+2011}{2011+2012}=\frac{2010}{2011+2012}+\frac{2011}{2011+2012}.\)
Ta có : \(\frac{2010}{2011+2012}< \frac{2010}{2011}\) và \(\frac{2011}{2011+2012}< \frac{2011}{2012}\)
=> \(\frac{2010+2011}{2011+2012}< \frac{2010}{2011}+\frac{2011}{2012}\)
=> A < B
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= 1999*(2011-1)/2010*(1998-1)
= 1999*2010/2010*1997
=1999/1997
\(\frac{1999\times2011-1999}{2010\times1998-2010}\)
\(=\frac{1999\times\left(2011-1\right)}{2010\times\left(1998-1\right)}\)
\(=\frac{1999\times2010}{2010\times1997}\)
\(=\frac{1999}{1997}\)
_Chúc bạn học tốt_