巧算:(1/2+1/3)-(1/3+1/4)+(1/4+1/5)-(1/5-1/6)-(1/6+
巧算:(1/2+1/3)-(1/3+1/4)+(1/4+1/5)-(1/5-1/6)-(1/6+
(1+1/2)*(1+1/4)*(1+1/6)*...*(1+1/2008)*(1-1/3)*(1-1/5)*(1-1/
(1+2/1)(1+4/1)(1+6/1).(1+10/)(1-3/1)(1—5/1).(1-9/1)
1.动脑筋计算:(1+1/2)*(1+1/4)*(1+1/6)*…* (1+1/10)*(1-1/3)*(1-1/5)*
1/2*1/3+1/3*1/4+1/4*1/5+1/5*1/6 (简便方法)
1/6【1/4{1/3(1/2X-1)+3}+5】=1
(1)1+1/2+1/3+1/4+1/5+1/6+1/7+1/14+1/28
(1-1/2)*(1-1/3)*(1-1/4)*(1-1/5)*(1-1/6)*…*(1-1/19)*(1-1/20)=
巧算2/1除以(3/1除以4/1·)除以(4/1除以5/1)除以(5/1除以6/1)除以(6/1除以7/1)
1/(1*3)+1/(2*4)+1/(3*5)+1/(4*6)+...+1/(8*10)=?
(1/2+1/3+1/4+1/5+1/6+.+1/2013)*(1+1/2+..+1/2012)-(1+1/2+1/3+
数列找规律!(1)1,2,-3,-4,5,6,-7,-8(2)-1,-1/2,1/3,1/4,-1/5,-1/6,1/7