Question

(1/8+1/9+1/10+1/11)X(1/9+1/10+1/11+1/12)-(1/8+1/9+1/10+1/11+1/12)X(1/9+1/10+1/11)

要答得准确和详细步骤

Answer 1

1/96 把1/8+1/9+1/10+1/11+1/12看做已知结果t.那么（t-1/12）*（t-1/8）-t*（t-1/8-1/12）展开就刚好消去t得出结果 =1/96

Answer 2

令a=1/9+1/10+1/11

(1/8+1/9+1/10+1/11)X(1/9+1/10+1/11+1/12)-(1/8+1/9+1/10+1/11+1/12)X(1/9+1/10+1/11)
=(1/8+a)*(a+1/12)-(1/8+a+1/12)*a
=(1/8+a)*(a+1/12)-(1/8+a)a-1/12*a
=(1/8+a)*a+1/12*(1/8+a)-(1/8+a)a-1/12*a
=1/12*(1/8+a)-1/12*a
=1/12*1/8+1/12*a-1/12*a
=1/96

Answer 3

(1/8+1/9+1/10+1/11)X(1/9+1/10+1/11+1/12)-(1/8+1/9+1/10+1/11+1/12)X(1/9+1/10+1/11)
=1/96