初一平方差的题(1-1/2^2)(1-1/3^2)(1-1/4^2)...(1-1/2009^2)(1-2010^2)=最后一个是(1-1/2010^2)
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初一平方差的题(1-1/2^2)(1-1/3^2)(1-1/4^2)...(1-1/2009^2)(1-2010^2)=最后一个是(1-1/2010^2)
初一平方差的题
(1-1/2^2)(1-1/3^2)(1-1/4^2)...(1-1/2009^2)(1-2010^2)=
最后一个是(1-1/2010^2)
初一平方差的题(1-1/2^2)(1-1/3^2)(1-1/4^2)...(1-1/2009^2)(1-2010^2)=最后一个是(1-1/2010^2)
最后一个是(1-1/2010^2)吧?
=[1-(1/2)^2][1-(1/3^2)]……[1-(1/2010)^2]
=(1-1/2)(1+1/2)(1-1/3)(1+1/3)……(1-1/2009)(1+1/2009)(1-1/2010)(1+1/2010)
=(1/2)(3/2)(2/3)(4/3)……(2008/2009)(2010/2009)(2009/2010)(2011/2010)=(1/2)(2011/2010)
=2011/4020
(1-1/2^2)(1-1/3^2)(1-1/4^2)…(1-1/2008^2)(1-1/2009^2) (1-1/2010^2)
=(1-1/2)*(1+1/2)*(1-1/3)(1+1/3)*(1-1/4)*(1+1/4)......(1-1/2008)*(1+1/2008)*(1-1/2009)*(1+1/2009) *(1-1/2010)*(1+1/2010)
=1/2 *...
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(1-1/2^2)(1-1/3^2)(1-1/4^2)…(1-1/2008^2)(1-1/2009^2) (1-1/2010^2)
=(1-1/2)*(1+1/2)*(1-1/3)(1+1/3)*(1-1/4)*(1+1/4)......(1-1/2008)*(1+1/2008)*(1-1/2009)*(1+1/2009) *(1-1/2010)*(1+1/2010)
=1/2 * 3/2 * 2/3 * 4/3 * 5/4......2007/2008 * 2008/2009 * 2010/2009
=1/2 * 2010/2009 *2011/2010
=1/2*2011/2009
=2011/4018
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