1/(2+4)+1/(4+6)+1/(6+8)+…1/(2010+2012)怎么做

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1/(2+4)+1/(4+6)+1/(6+8)+…1/(2010+2012)怎么做
1/(2+4)+1/(4+6)+1/(6+8)+…1/(2010+2012)怎么做

1/(2+4)+1/(4+6)+1/(6+8)+…1/(2010+2012)怎么做
1/(2*4)+1/(4*6)+1/(6*8)+…1/(2010*2012)
=(1/2-1/4+1/4-1/6+1/6-1/8+……+1/2010-1/2012)÷2
=(1/2-1/2012)÷2
=1005/2012÷2
=1005/4024

1/(2+4)=1/2*(1/2-1/4)
1/(4+6)=1/2*(1/4-1/6)
.......
1/(2010+2012)=1/2*(1/2010-1/2012)

所以1/(2+4)+1/(4+6)+1/(6+8)+…1/(2010+2012)=1/2*(1/2-1/4+1/4-1/6+...+1/2010-1/2012)=1/2*(1/2-1/2012)=1005/4024

=1/2(1-1/2)+1/2(1/2-1/3)+1/2(1/3-1/4)+......+1/2(1/1005-1/1006)
=1/2(1-1/2+1/2-1/3+1/3-1/4+........+1/1005-1/1006)
=1/2(1-1/1006)
=1/2*1005/1006
=1005/2012