求助一道数学题,急!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Question

2-2分之1-6分之1-12分之1-20分之1-30分之1-42分之1-56分之1(请告诉我过程,谢谢!,要求用简便方法解)

Answer 1

2-1/2-1/6-1/12-1/20-1/30-1/42-1/56
=2-1/2-(1/2)*(1/3)-(1/3)*(1/4)-(1/4)*(1/5)-(1/5)*(1/6)-(1/6)*(1/7)-(1/7)*(1/8)
=2-1/2-(1/2-1/3)-(1/3-1/4)-(1/4-1/5)-(1/5-1/6)-(1/6-1/7)-(1/7-1/8)
=2-1/2-1/2+1/3-1/3+1/4-1/4+1/5-1/5+1/6-1/6+1/7-1/7+1/8
=2-1+1/8
=1又1/8

Answer 2

没有意义啊
因为第一个2-2作分母为0，整个式子就没意义了

Answer 3

确实

Answer 4

2-1/2-1/(2*3)-1/(3*4)-1/(4*5)-1/(5*6)-1/(6*7)-1/(7*8)=2-1/2-(1/2-1/3)-(1/3-1/4)-(1/4-1/5)-(1/5-1/6)-(1/6-1/7)-(1/7-1/8)=1+1/8=9/8

Answer 5

赞成