(1+1/2)(1+1/3)(1+1/4).....(1+1/2023). giup vssss
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Ta có: C = 1/1.2.3 + 1/2.3.4 + 1/3.4.5 + ... + 1/2021.2022.2023
=> C = 1/2. (3-1/1.2.3 + 4-2/2.3.4 + 5-3/3.4.5 + ... + 2023-2021/2021.2022.2023
=> C = 1/2. (1/1.2 - 1/2.3 + 1/2.3 - 1/3.4 + 1/3.4 - 1/4.5 + ... + 1/2021.2022 - 1/2022.2023)
=> C = 1/2. (1/1.2 - 1/2022.2023)
- Phần còn lại bạn tự tính chứ số to quá
Ta có: \(B=\frac12+\frac13-\frac14+\frac15-\frac16+\cdots-\frac{1}{2022}+\frac{1}{2023}\)
=>\(B=\frac12+\frac13+\frac14+\frac15+\frac16+\cdots+\frac{1}{2022}+\frac{1}{2023}-2\left(\frac14+\frac16+\cdots+\frac{1}{2022}\right)\)
\(=\frac12+\frac13+\frac14+\frac15+\cdots+\frac{1}{2022}+\frac{1}{2023}-\frac12-\frac13-\cdots-\frac{1}{1011}\)
\(=\frac{1}{1012}+\frac{1}{1013}+\cdots+\frac{1}{2022}+\frac{1}{2023}\)
=C
=>B-C=0
bất kì số nào nhân với 0 cũng = 0
Nên là câu đó bằng 0 nha
Lời giải:
Gọi tổng trên là $A$
$A=\frac{1}{\frac{3.4}{2}}+\frac{1}{\frac{4.5}{2}}+....+\frac{1}{\frac{2023.2024}{2}}$
$=\frac{2}{3.4}+\frac{2}{4.5}+...+\frac{2}{2023.2024}$
$=2(\frac{4-3}{3.4}+\frac{5-4}{4.5}+...+\frac{2024-2023}{2023.2024})$
$=2(\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+....+\frac{1}{2023}-\frac{1}{2024})$
$=2(\frac{1}{3}-\frac{1}{2024})=\frac{2021}{3036}$
\(\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times...\times\left(1-\dfrac{1}{2023}\right)\\ =\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times...\times\dfrac{2022}{2023}\\ =\dfrac{1}{2023}\)
1+1/2.(1+2)+1/3.(1+2+3)+1/4.(1+2+3+4)+...+1/2023.(1+2+3+...+2023)
=1+1/2.(1+2).2/2+1/3.(1+3).3/2+1/4.(1+4).4/2+...+1/2023.(1+2+3+...+2023).2023/2
=2/2+3/2+4/2+...+2023/2
=2+3+4+...+2023/2
=2025.2022/2/2
=1023637,5
tham khảo thôi nha
Ta có: \(1+\frac12\left(1+2\right)+\frac13\left(1+2+3\right)+\cdots+\frac{1}{2023}\left(1+2+\cdots+2023\right)\)
\(=1+\frac12\cdot\frac{2\cdot3}{2}+\frac13\cdot\frac{3\cdot4}{2}+...+\frac{1}{2023}\cdot\frac{2023\cdot2024}{2}\)
\(=1+\frac32+\frac42+\cdots+\frac{2024}{2}=\frac12\left(2+3+4+\cdots+2024\right)\)
\(=\frac12\left(2024-2+1\right)\cdot\frac{\left(2024+2\right)}{2}=\frac12\cdot2023\cdot\frac{2026}{2}=\frac{2023}{2}\cdot1013\)
=\(\frac{2049299}{2}\)
\(A=1-3+5-7+......-2019+2021-2023\)
\(A=\left(1-3\right)+\left(5-7\right)+....+\left(2021-2023\right)\)
\(A=-2+\left(-2\right)+....+\left(-2\right)\left(506 cặp\right)\)
\(A=-2.506\)
\(A=-1012\)
*) A=(1-3)+(5-7)+....+(2021-2023)
<=> A=-2+(-2)+...+(-2)
Dãy A có (2023-1):2+1=1012 số số hạng
=> Có 506 số (-2)
=> A=(-2).506=-1012
A = (1 + \(\frac12\)).(1 + \(\frac13\)).(1 + \(\frac14\))....(1 + \(\frac{1}{2024}\))
A = \(\frac{2+1}{2}\).\(\frac{3+1}{3}\)+...+\(\frac{2003+1}{2003}\)
A = \(\frac32\).\(\frac43\)...\(\frac{2024}{2003}\)
A = \(\frac{2024}{2}\)
A = 1012
Ta có:
$(1+\dfrac{1}{2})(1+\dfrac{1}{3})(1+\dfrac{1}{4})\cdots(1+\dfrac{1}{2023})$
$= \dfrac{3}{2}\cdot \dfrac{4}{3}\cdot \dfrac{5}{4}\cdots \dfrac{2024}{2023}$
$= \dfrac{3\cdot 4\cdot 5 \cdots 2024}{2\cdot 3\cdot 4 \cdots 2023}$
$= \dfrac{2024}{2}$
$= 1012$
Vậy giá trị bằng $1012$.