学生姓名孔子悦年级小六授课时间2013年5月16日教师姓名杨勇飞课时2课题复习简便计算教学目标掌握简便运算的方法重点掌握简便运算的方法难点掌握简便运算的方法×+×+×1/(1×2×3×4)+1/(2×3×4×5)+1/(3×4×5×6)+...+1/(7×8×9×10)=(1/3)×[1/(1×2×3)-1/(2×3×4)]+(1/3)×[1/(2×3×4)-1/(3×4×5)]+(1/3)×[1/(3×4×5)-1/(4×5×6)]+...+(1/3)×[1/(7×8×9)-1/(8×9×10)]=(1/3)×[1/(1×2×3)-1/(2×3×4)+1/(2×3×4)-1/(3×4×5)+1/(3×4×5)-1/(4×5×6)+...+1/(7×8×9)-1/(8×9×10)]=(1/3)×[1/(1×2×3)-1/(8×9×10)]=(1/3)×[(1/6)-(1/720)]=(1/3)×(119/720)=119/2160仅供参考:(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)设1+1/2+1/3+1/4+1/5=a1/2+1/3+1/4+1/5=b(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)=a*(b+1/6)-(a+1/6)*b=1/6(a-b)=1/6 4/3-7/12+9/20-11/30+13/42-15/56=(1+1/3)-(1/3+1/4)+(1/4-1/5)-(1/5+1/6)+(1/6+1/7)-(1/7+1/8)=1-1/8=7/81+3+5+7+9+11............+199=(1+199)*100/2=200*100/2=10000(1x2x3+3x6x9+7x14x21)/(1x3x5+3x9x15+7x21x35)=3(1×2+6×9+7×14×7)/3(1×5+9×15+7×7×35)=(1×2+6×9+7×14×7)/(1×5+9×15+7×7×35)=14(4+7×7)/5(1+3×9+7×7×7)=14×53/5×7(4+7×7)=14×53/35×53=14/35
小学奥数计算题简便计算 来自淘豆网m.daumloan.com转载请标明出处.
