①(1+½)×(1-½)×(1+1/3)×(1-1/3)×(1+1/4)×(1-1/4)×......(1+1/99)×(
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①(1+½)×(1-½)×(1+1/3)×(1-1/3)×(1+1/4)×(1-1/4)×......(1+1/99)×(1+1/99)
=[(1+½)×(1+1/3 )×(1+1/4)×......×(1+1/99)]×[(1-½)×(1-1/3)×(1-1/4)×......×(1-1/99)]
=(3/2*4/3*5/4*......*100/99)*(1/2*2/3*3/4*......*98/99)
=100/2*1/99
=50/99
②2009×20102010+2010×20092009
=10001*2*2009*2010
=80769876180
=[(1+½)×(1+1/3 )×(1+1/4)×......×(1+1/99)]×[(1-½)×(1-1/3)×(1-1/4)×......×(1-1/99)]
=(3/2*4/3*5/4*......*100/99)*(1/2*2/3*3/4*......*98/99)
=100/2*1/99
=50/99
②2009×20102010+2010×20092009
=10001*2*2009*2010
=80769876180
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