简便计算题1/3+4/(3*5)+6/(3*5*7)+8/(3*5*7*9)+10/(3*5*7*9*11)+1/(3*5*7*9*11)
问题描述:
简便计算题1/3+4/(3*5)+6/(3*5*7)+8/(3*5*7*9)+10/(3*5*7*9*11)+1/(3*5*7*9*11)
答
10/(3*5*7*9*11)+1/(3*5*7*9*11)=1/(3*5*7*9)从后依次往前算
答
1/3+4/(3*5)+6/(3*5*7)+8/(3*5*7*9)+10/(3*5*7*9*11)+1/(3*5*7*9*11)
=1/3+4/(3*5)+6/(3*5*7)+8/(3*5*7*9)+1/(3*5*7*9*11)*(10+1)
=1/3+4/(3*5)+6/(3*5*7)+8/(3*5*7*9)+11/(3*5*7*9*11)
=1/3+4/(3*5)+6/(3*5*7)+8/(3*5*7*9)+1/(3*5*7*9)
=1/3+4/(3*5)+6/(3*5*7)+1/(3*5*7*9)*(8+1)
=1/3+4/(3*5)+6/(3*5*7)+9/(3*5*7*9)
=1/3+4/(3*5)+6/(3*5*7)+1/(3*5*7)
=1/3+4/(3*5)+1/(3*5*7)*(6+1)
=1/3+4/(3*5)+7/(3*5*7)
=1/3+4/(3*5)+1/(3*5)
=1/3+1/(3*5)*(4+1)
=1/3+1/(3*5)*5
=1/3+1/3
=2/3