You're welcome.
因为1/(1*2) + 1/(2*3) +1/(3*4) + 1/(4*5) +.+ 1/(9*10)= 1-1/10
把右边的1/10移到左边即可:
所以1/2+1/6+1/12+1/20+...+1/90 + 1/10 = 1
You're welcome.
因为1/(1*2) + 1/(2*3) +1/(3*4) + 1/(4*5) +.+ 1/(9*10)= 1-1/10
把右边的1/10移到左边即可:
所以1/2+1/6+1/12+1/20+...+1/90 + 1/10 = 1