已知|ab-2|与|b-1|互为相反数,试求代数式1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+…+1/(a+2008)(b+2008)
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|ab-2|与|b-1|互为相反数, 因绝对值不可能为负数, 所以 |ab-2|与|b-1|均为0, b=1, a=2.
1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+…+1/(a+2008)(b+2008)
=1/1*2 + 1/2*3 + 1/3*4 + ... + 1/2009*2010
=(1 - 1/2) + (1/2 - 1/3) + (1/3 - 1/4) + ... + (1/2009 - 1/2010)
=1-1/2010
=2009/2010
1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+…+1/(a+2008)(b+2008)
=1/1*2 + 1/2*3 + 1/3*4 + ... + 1/2009*2010
=(1 - 1/2) + (1/2 - 1/3) + (1/3 - 1/4) + ... + (1/2009 - 1/2010)
=1-1/2010
=2009/2010
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