分式的化简:1/a-1 + 1/(a-1)(a-2) + 1/(a-2)(a-3) +.+ 1/(a-99)(a-100)清晰点,一般的我是明白的!

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分式的化简:1/a-1 + 1/(a-1)(a-2) + 1/(a-2)(a-3) +.+ 1/(a-99)(a-100)
清晰点,
一般的我是明白的!

1=(a-1)-(a-2)
所以1/(a-1)(a-2)=[(a-1)-(a-2)]/(a-1)(a-2)=(a-1)/(a-1)(a-2)-(a-2)/(a-1)(a-2)=1/(a-2)-1/(a-1)
同理,1=(a-2)-(a-3),得到1/(a-2)(a-3)=1/(a-3)/1/(a-2)
后面以此类推
所以原式=1/(a-1)+1/(a-2)-1/(a-1)+1/(a-3)/1/(a-2)+……+1/(a-100)-1/(a-99)
=1/(a-100)


1/(a-1) + 1/(a-1)(a-2) + 1/(a-2)(a-3) +.....+ 1/(a-99)(a-100)
=1/(a-1) + [1/(a-2)-1/(a-1)]+ [1/(a-3))-1/(a-2)]+.....+ [1/(a-100)-1/(a-99)]
=1/(a-100)