梁斯丝东方古韵mp4:初一数学问题

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运用因式分解的方法计算:
(1-1/2^2)(1-1/3^2)(1/4^2)……(1-1/2004^2)(1-1/2005^2)
要过程,捣乱者封号!

原式
=[(1*3)/(2*2)]*[(2*4)/(3*3)]*[(3*5)/(4*4)]*....*[(2004*2006)/(2005*2005)]
=(1/2)*(3/2)*(2/3)*(4/3)*(3/4)*(5/4)*....*(2004/2005)*(2006/2005)
=(1/2)*[(3/2)*(2/3)]*[(4/3)*(3/4)]*[(5/4)*....*(2004/2005)]*(2006/2005)
=(1/2)*(2006/2005)
=1003/2005

原式=(1-1/2)(1+1/2)(1-1/3)(1+1/3)(1-1/4)………(1-1/2005)(1+1/2005)
=1/2 * 3/2 * 2/3 * 4/3 * 3/4 *……*2004/2005 *2006/2005
=1/2 * 2006/2005
=1003/2005