(1+1/2+1/3)×(1/2+1/3+1/4)-(1+1/2+1/3+1/4)×(1/2+1/3)=()

2023-06-15

A. 1/2
B. 1/3
C. 1/4
D. 1/5


参考答案:C

(1+1/2+1/3)×(1/2+1/3+1/4)=(1+1/2+1/3+1/4—1/4) ×(1/2+1/3+1/4) =(1+1/2+1/3+1/4)×(1/2+1/3)+(1+1/2+1/3+1/4)×(1/4)—(1/4) ×(1/2+1/3+1/4)=(1+1/2+1/3+1/4)×(1/2+1/3)+1/4,因此(1+1/2+1/3)×(1/2+1/3+1/4)—(1+1/2+1/3+1/4)×(1/2+1/3)=1/4。故答案为C。

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