1/1-1/2+1/2-1/3+1/3-...-1/2020+1/2020-1/2021
=1/1+(1/2-1/2)+(1/3-1/3)+...+(1/2020-1/2020)-1/2021
=1/1-1/2021
=1-1/2021
=2020/2021
Học tốt nha!!!
Câu 24: Cho biểu thức: A=1/2+1/3+1/4+.........+1/2021+1/2022 Và B=2021/1+2020/2+2019/3+.........+3/2019+2020+1/2021
(1-1/2020).(1-2/2020).(1-3/2020)...(1-2021/2020) Giúp tui đi, mốt thi rồi
So sánh:
A=2021^2020+2/2021^2020-1 và B=2021^2020/2021^2020-3
a,1/2+1/3+1/4+...+1/2020
b,1/2+1/2^2+...+1/2^109
c,1/1*2+1/2*3+...1/2020*2021
Cho B 1.2.3.....2020.(1+1/2+1/3+........+1/2020) Chứng minh rằng B chia hết cho 2021.
Cho A = 1/2+1/3+1/4+...+1/2022 và
B = 2021/1+2020/2+2019/3+...+1/2021.
hứa cho đúng
so sánh b=1/2022+2/2021+3/2020+...+2021/2+2022/1 VÀ c=1/2+1/3+1/4+...+1/2022+1/2023
A=(-1)×(-1)^2×(-1)^3×(-1)^4×......× (-1)^2020×(-1)^2021
Nếu 1/3 + 1/6 +1/10 + ...... + 1/x.(x+1) : 2 = 2019/2021
A.x = 2019/2020 B. x = 2019 C. x = 2020 D. x = 2021
