(1-1/2的2次方)(1-1/3的2次方).(1-1/10的2次方)
=(1-1/2)(1+1/2)(1-1/3)(1+1/3).(1-1/10)(1+1/10)
=1/2x3/2x2/3x4/3...x9/10x11/10
=1/2x11/10
=11/20
(1-1/2的2次方)(1-1/3的2次方).(1-1/10的2次方)
=(1-1/2)(1+1/2)(1-1/3)(1+1/3).(1-1/10)(1+1/10)
=1/2x3/2x2/3x4/3...x9/10x11/10
=1/2x11/10
=11/20