(1+12)×(1−12)×(1+13)×(1−13)×⋯×(1+110)×(1−110)=()()\left(1+\frac{1}{2}\right) \times \left(1-\frac{1}{2}\right) \times \left(1+\frac{1}{3}\right) \times \left(1-\frac{1}{3}\right) \times \cdots \times \left(1+\frac{1}{10}\right) \times \left(1-\frac{1}{10}\right) = \frac{(\quad)}{(\quad)}

Worked solution

1. 将各个括号内的算式分别计算为最简分数

计算每个括号内的加减法:
(1+12)=32,(1−12)=12\left(1+\frac{1}{2}\right) = \frac{3}{2},\quad \left(1-\frac{1}{2}\right) = \frac{1}{2}
(1+13)=43,(1−13)=23\left(1+\frac{1}{3}\right) = \frac{4}{3},\quad \left(1-\frac{1}{3}\right) = \frac{2}{3}
⋯\cdots
(1+110)=1110,(1−110)=910\left(1+\frac{1}{10}\right) = \frac{11}{10},\quad \left(1-\frac{1}{10}\right) = \frac{9}{10}
代入原式得:
原式=32×12×43×23×⋯×1110×910\text{原式} = \frac{3}{2} \times \frac{1}{2} \times \frac{4}{3} \times \frac{2}{3} \times \cdots \times \frac{11}{10} \times \frac{9}{10}

2. 运用乘法交换律与结合律对项进行分组并约分

将加法项与减法项分别分组重组:
原式=(32×43×54×⋯×1110)×(12×23×34×⋯×910)\text{原式} = \left(\frac{3}{2} \times \frac{4}{3} \times \frac{5}{4} \times \cdots \times \frac{11}{10}\right) \times \left(\frac{1}{2} \times \frac{2}{3} \times \frac{3}{4} \times \cdots \times \frac{9}{10}\right)
第一组交叉约分后保留第一个分母与最后一个分子:
32×43×54×⋯×1110=112\frac{3}{2} \times \frac{4}{3} \times \frac{5}{4} \times \cdots \times \frac{11}{10} = \frac{11}{2}
第二组交叉约分后保留第一个分子与最后一个分母:
12×23×34×⋯×910=110\frac{1}{2} \times \frac{2}{3} \times \frac{3}{4} \times \cdots \times \frac{9}{10} = \frac{1}{10}

3. 计算两组结果的乘积得到最终答案

将化简后的两部分相乘:
原式=112×110=1120\text{原式} = \frac{11}{2} \times \frac{1}{10} = \frac{11}{20}

Answer

1120\frac{11}{20}

AI analysis — may contain mistakes.

Worked this one out on paper? Snap your steps and Gigle's AI math checker will circle the step where it went wrong.

More questions on this topic

  1. 1Find the value of the expression 100−98+96−94+92−90+⋯+8−6+4−2100 - 98 + 96 - 94 + 92 - 90 + \cdots + 8 - 6 + 4 - 2. A. 20 B. 40 C. 50 D. 80 E. 100
  2. 2What is the value of the product (1⋅32⋅2)(2⋅43⋅3)(3⋅54⋅4)⋯(97⋅9998⋅98)(98⋅10099⋅99)(\frac{1 \cdot 3}{2 \cdot 2})(\frac{2 \cdot 4}{3 \cdot 3})(\frac{3 \cdot 5}{4 \cdot 4}) \cdots (\frac{97 \cdot 99}{98 \cdot 98})(\frac{98 \cdot 100}{99 \cdot 99})…
  3. 3What is the ones digit of the value of the below expression? 222222−22222−2222−222−22−2222222 - 22222 - 2222 - 222 - 22 - 2 A. 0 B. 2 C. 4 D. 6…
  4. 4For positive integer nn, the factorial notation n!n! represents the product of the integers from nn to 1. (For example…
  5. 5What is the value of the following expression ? 1−2+3−4+5+6−7+8−9+10+11−121 - 2 + 3 - 4 + 5 + 6 - 7 + 8 - 9 + 10 + 11 - 12 A. 7 B. 10 C. 13 D. 1…