(1/8)+(1/24)+(1/48)…+(1/2400)+(1/2600)
=1/(2×4)+1/(4×6)+……+1/(48×50)+1/(50×52)
=1/2×(1/2-1/4+1/4-1/6+……+1/50-1/52)
=1/2×(1/2-1/52)
=1/2×25/52
=25/104
解答:
1/8)+(1/24)+(1/48)…+(1/2400)+(1/2600
=1/(2*4)+1/(4*6)+1/(6*8)+……+1/(48*50)+1/(50*52)
=(1/2)[2/(2*4)+2/(4*6)+2/(6*8)+……+2/(48*50)+2/(50*52)]
=(1/2)(1/2-1/4+1/4-1/6+1/6-1/8+……+1/48-1/50+1/50-1/52)
=(1/2)(1/2-1/52)
=25/104