A=(1 – 1/1+2) x (1-1/1+2+3) x (1-1/1+2+3) x (1-1/1+2+3)x1-1/1+2+3+4)x … x (1-1/1+2+3+…+2018)
GIÚP MK VS MK CẦN GẤP
VOTE 5 SAO +CẢM ƠN
A=(1 – 1/1+2) x (1-1/1+2+3) x (1-1/1+2+3) x (1-1/1+2+3)x1-1/1+2+3+4)x … x (1-1/1+2+3+…+2018) GIÚP
By Delilah
Đáp án:
Giải thích các bước giải:
A=1/1+2 + 1/1+2+3 + 1/1+2+3+4 +…+1/1+2+3+4+…+2020
=2/2×3+2/3×4+2/4×5+..+2/2020×2021
=2(1/2-1/3+1/3-1/4+1/4-1/5+..+1/2020-1/2021)
=2(1/2-1/2021)=2.2019/4041=2019/2021
A=1/1+2 + 1/1+2+3 + 1/1+2+3+4 +…+1/1+2+3+4+…+2020
=2/2×3+2/3×4+2/4×5+..+2/2020×2021
=2(1/2-1/3+1/3-1/4+1/4-1/5+..+1/2020-1/2021)
=2(1/2-1/2021)=2.2019/4041=2019/2021