3,0,1,5,1,5,7,2,49,,,

(7×1-3×1)+(7×3-3×2)+(7×5-3×3)+.+(7×49-3×25) 1/49+3/49+5/49+7/49+9/49+11/49+13/49 简便运算 还求思路 急... 1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8...1/49*50 1/(1*3)+1/(3*5)+1/(5*7).+1/(49*51)=多少 1×3/1+3×5/1+5×7/1……+49×51/1 (1×3)分之1+(3×5)分之1+(5×7)分之1+.+(49×51)分之1 1/1*3+1/3*5+1/5*7+...+1/49*51 1/1×3+1/3×5+1/5×7+.+1/49×51=多少? 1/1*3+1/3*5+1/5*7+.+1/49*51怎么计算 1/1×3+1/3×5+1/5×7+……+1/47×49 行列式5阶计算2,-1,1,5,0, 10,-8,7,3,2 0, 2,1,3,0 0,-1,5,1,0 0,3,-1, 24除以1/3减56 1/2*[(1/3+5/6)除以5/7｝ 49/5*7/8除以7 全体简算