1+3+5+7+9``````+19=10*10,用一个含N的式子表示这一规律

1/1*3+1/3*5+1/5*7+1/7*9+...1/17*19= (1+3)/1+(3+5)/1+(5+7)/1+(7+9)/1.+(17+19/1+(19+21)/1=? 1+3+5+7+9+.+19=多少?急 1*3*5+3*5*7+5*7*9+……+17*19*21=? 1*3*5+3*5*7+5*7*9+…+19*21*23=? 数学计算题：1*3+3*5+5*7+7*9+...+17*19=? 因为1/1*3=1/2*（1-1/3）,1/3*5=1/2*(1/3-1/5),1/5*7=1/2*(1/5-1/7),.,1/17*19=1/2*(1/17-1/19)所以1/1*3+1/3*5+1/5*7+...+1/17*19=1/2*(1-1/3)+1/2*(1/3-1/5)+1/2*(1/5-1/7)+...+1/2*(1/17-1/19)=1/2*(1-1/3+1/3-1/5+1/5-1/7+...+1/17-1/19)=1/2*(1-1/19)=9/19(1 1/1×3＋1/3×5+1/5×7+…+1/17×19+1/9×21=? 计算1/(1×3)+1/(3×5)+1/(5×7)+1/(7×9)+.+1/(19×21) -1/1*3-1/3*5-1/5*7-1/7*9-^-1/19*21 1/3*1+1/3*5+1/5*7+----1/17*19+1/19*21= 已知1/3-1/5=1/3*5,计算:3*5+1/5*7+1/7*9+……+1/19*21 1/3-1/5=2/3*5,计算1/3*5+1/5*7+1/7*9+…+1/19*21急 (1+3+5+7+9+.+19)--(2+4+6+8+.+18) = =.递等式 急. 1/1*3+1/3*5+1/5*7+1/7*9+1/9*11+1/11*13+1/13*15+1/15*17+1/17*19+1/19*21= 7+1+2=321 4+5-1=416 9+5-4=19 4+2+3=? 1/1x3=1/2(1-1/3),1/3x5=1/2(1/3-1/5),1/5x7=1/2(1/5-1/7),……,1/17x19=1/2(1/17-1/19).∴1/1x3+1/3x5+1/5x7+……+1/17x19=1/2(1-1/3)+1/2(1/3-1/5)+1/2(1/5-1/7)+……+1/2(1/17-1/19)=1/2 (1-1/3+1/3-1/5+1/5-1/7+……+1/17-1/19)=1/2(1-1/19)=9/19根据以 5+3=28 9+1=810 8+6=214 5+4=19 7+3=?