上述为
(1-2)/2*(1-3)/3*(1-4)/4*(1-5)/5*(1-6)/6*(1-7)/7
=(-1*-2*-3*-4*-5*-6)/(2*3*4*5*6*7)
=1/7
原式=(-1/2)×(-2/3)×(-3/4)×(-4/5)×(-5/6)×(-6/7) 分子分母也约去 又有6个数所以结果是正数 解得原式=1/7
(1/2-1)×(1/3-1)×(1/4-1)×(1/5-1)×(1/6-1)×(1/7-1)
=(-1/2)×(-2/3)×(-3/4)×(-4/5)×(-5/6)×(-6/7)
约分
=1/7
(1/2-1)×(1/3-1)×(1/4-1)×(1/5-1)×(1/6-1)×(1/7-1)
=(1-1/2)×(1-1/3)×(1-1/4)×(1-1/5)×(1-1/6)×(1-1/7)
=1/2*2/3*3/4*4/5*5/6*6/7
=1/7
=(-1/2)×(-2/3)×(-3/4)×(-4/5)×(-5/6)×(-6/7)
=1/7