原式
=1/2x(2/2x4+2/4x6+2/6x8+···+2/2012x2014)
=1/2x(1/2-1/4+1/4-1/6+1/6-1/8+···+1/2012-1/2014)
=1/2x(1/2-1/2014)
=1/2x1006/2014
=1003/2014嗯，不错不错，点赞
加好友啊