过程
1.2011X2011-2010X2012
=2011²-(2011-1)(2011+1)
=2011²-(2011²-1)
=2011²-2011²+1
=1
2.1990X1999-1989X2000
=1990X1999-(1990-1)X(1999+1)
=1990X1999-(1990X1999+1990-1999-1)
=1990X1999-1990X1999-1990+1999+1
=-1990+1999+1
=10
3.20052005/20042004
=(2005X10001)/(2004X10001)
=2005/2004
4.2003²-2002X2004
=2003²-(2003-1)(2003+1)
=2003²-(2003²-1)
=2003²-2003²+1
=1
5.(1993X1994-1)/(1993+1992X1994)
=[1993X(1993+1)-1]/[1993+(1993-1)X(1993+1)]
=[1993²+1993-1]/[1993+1993²-1]
=1
6.5/6-6/12+7/20-9/30
=10/12-6/12+21/60-18/60
=4/12+3/60
=20/60+3/60
=23/60
7.7/12-9/20+11/30-13/42+15/56-17/72
=7/12-17/72-9/20+11/30-13/42+15/56
=42/72-17/72-27/60+22/60-42/168+45/168
=25/72-5/60+3/168
=25/72-1/12+1/56
=25/72-6/72+1/56
=19/72+1/56
=133/504+9/504
=142/504
=71/252
=2011²-(2011-1)(2011+1)
=2011²-(2011²-1)
=2011²-2011²+1
=1
2.1990X1999-1989X2000
=1990X1999-(1990-1)X(1999+1)
=1990X1999-(1990X1999+1990-1999-1)
=1990X1999-1990X1999-1990+1999+1
=-1990+1999+1
=10
3.20052005/20042004
=(2005X10001)/(2004X10001)
=2005/2004
4.2003²-2002X2004
=2003²-(2003-1)(2003+1)
=2003²-(2003²-1)
=2003²-2003²+1
=1
5.(1993X1994-1)/(1993+1992X1994)
=[1993X(1993+1)-1]/[1993+(1993-1)X(1993+1)]
=[1993²+1993-1]/[1993+1993²-1]
=1
6.5/6-6/12+7/20-9/30
=10/12-6/12+21/60-18/60
=4/12+3/60
=20/60+3/60
=23/60
7.7/12-9/20+11/30-13/42+15/56-17/72
=7/12-17/72-9/20+11/30-13/42+15/56
=42/72-17/72-27/60+22/60-42/168+45/168
=25/72-5/60+3/168
=25/72-1/12+1/56
=25/72-6/72+1/56
=19/72+1/56
=133/504+9/504
=142/504
=71/252
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第1个回答 2012-05-02
1.2011X2011-2010X2012
=2011²-(2011-1)(2011+1)
=2011²-(2011²-1)
=2011²-2011²+1
=1
2.1990X1999-1989X2000
=1990X1999-(1990-1)X(1999+1)
=1990X1999-(1990X1999+1990-1999-1)
=1990X1999-1990X1999-1990+1999+1
=-1990+1999+1
=10
3.20052005/20042004
=(2005X10001)/(2004X10001)
=2005/2004
4.2003²-2002X2004
=2003²-(2003-1)(2003+1)
=2003²-(2003²-1)
=2003²-2003²+1
=1
=2011²-(2011-1)(2011+1)
=2011²-(2011²-1)
=2011²-2011²+1
=1
2.1990X1999-1989X2000
=1990X1999-(1990-1)X(1999+1)
=1990X1999-(1990X1999+1990-1999-1)
=1990X1999-1990X1999-1990+1999+1
=-1990+1999+1
=10
3.20052005/20042004
=(2005X10001)/(2004X10001)
=2005/2004
4.2003²-2002X2004
=2003²-(2003-1)(2003+1)
=2003²-(2003²-1)
=2003²-2003²+1
=1
第2个回答 2012-05-02
先做第一题:2011^2-(2011-1)(2011+1)=2011^2-2011^2+1=1其它触类旁通