1/2=1/1-1/2;1/6=1/2-1/3;1/12=1/3-1/4.根据以上规律,计算：1/2+1/6+1/12+20/1+30/1+1/42+1/561/2=1/1-1/2;1/6=1/2-1/3;1/12=1/3-1/4.根据以上规律,计算：1/2+1/6+1/12+1/20+1/30+1/42+1/56

1*1/2=? 1+1=2? 1+1=2? 1+1×2=? 2-1=1 2+1+2+6= Sn=1/(2^2-1)+1/(4^2-1)+1/(6^2-1)+.+1/[(2n)^2-1]求和 1+2+1+2+1+2+1+2+1+2+1+2+1+2 =( )*( ) =() 巧算：(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)===== (1-1/2)+(1-1/6)+(1-1/12)+...+(1-1/110)=? 1-1/2+1/3-1/4+1/5-1/6+1/7.-1/50=? 1/2+1/6+1/12+...+1/56=快 1/2+1/6+1/12+1/20= 1+1/2+1/6+1/16=? 1/2+1/6+1/12+…+1/1560=? 1*2*3+1-1+1/6=? 已知1/2=1-1/2,1/6=1/2-1/3,请计算1/2-1/6-1/12-1/20...-1/132 1-1/2+1/3-1/4+1/5-1/6+…+1/15=23*[1/( )+1/( )+1/( )+1/( )]