Tính nhanh 1 – 1/2 + 2-2/3 + 3-3,4 + 4- 1/4 – 3- 1/3 – 2- 1 /2 – 1

0 bình luận về “Tính nhanh 1 – 1/2 + 2-2/3 + 3-3,4 + 4- 1/4 – 3- 1/3 – 2- 1 /2 – 1”

1. `1−1/2 +2−2/3 +3−3/4 +4−1/4 −3−1/3 −2−1/2 −1`

   `=(1−1)−(1/2 +1/2 )+(2−2)−(2/3 +1/3 )+(3−3)−(3/4 +1/4 )−1`

   `=−1−1−1+4=1` 

   $#JAW#$

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2. 1−12+2−23+3−34+4−14−3−13−2−12−11−12+2−23+3−34+4−14−3−13−2−12−1

   =(1−1)−(12+12)+(2−2)−(23+13)+(3−3)−(34+14)−1=(1−1)−(12+12)+(2−2)−(23+13)+(3−3)−(34+14)−1

   =−1−1−1+4=1=−1−1−1+4=1 

    

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