1/1×3+1/3×5+1/5×7+…………+1/49×51和1/2×4+1/4×6+1/6×8+…………1/48×50
问题描述:
1/1×3+1/3×5+1/5×7+…………+1/49×51和1/2×4+1/4×6+1/6×8+…………1/48×50
接着 还有1/1+2 + 1/1+2+3 +……+ 1/1+2+3+……+100
我明天上课用
答
1/1×3+1/3×5+1/5×7+…………+1/49×51=(1-1/3+1/3-1/5+1/5-1/7+……+1/49-1/51)÷2=(1-1/51)÷2=50/51÷2=25/511/2×4+1/4×6+1/6×8+…………1/48×50=(1/2-1/4+1/4-1/6+1/6-1/8+……+1/49-1/50)÷2=(...