國一數學分數四則運算進階題 求解?

Sol
1
1/(2*3)+1/(3*4)+1/(4*5)+…+1/(99*100)
=(1/2－1/3)+(1/3－1/4)+(1/4－1/5)+…+(1/99－1/100)
=1/2－1/100
=49/100
2
2/(2*4)+2/(4*6)+2/(6*8)+…+2/(98*100)
=(1/2－1/4)+(1/4－1/6)+(1/6－1/8)+…+(1/98－1/100)
=1/2－1/100
=49/100