2021/2022 + 2020/2021 + 2019/2020 + 2018/2019 + 2017/2018 rôì so sánh với 5
Bài 3: Không quy đồng hãy so sánh các phân số sau: a, 2019/2020 và 2021/2022 b, 2019/2017 và 2021/2019 c, 201/202 và 135/137 d, 2019/2018 và 2021/2019
So sánh A=\(\dfrac{2018}{2019}\)+\(\dfrac{2019}{2020}\)+\(\dfrac{2020}{2021}\)+\(\dfrac{2021}{2018}\)với 4
Lời giải:
$A=1-\frac{1}{2019}+1-\frac{1}{2020}+1-\frac{1}{2021}+1+\frac{3}{2018}$
$=4+(\frac{1}{2018}-\frac{1}{2019}+\frac{1}{2018}-\frac{1}{2020}+\frac{1}{2018}-\frac{1}{2021})$
$> 4+0+0+0+0=4$
A=2017/2018+2020/2019
B=2018/2019+2021/2020
So sánh A và B
Xét 2017 /2018 và 2018/2019
1-2017/2018=1/2018
1-2018/2019=1/2019
mà 1/2018>1/2019=>2017/2018<2018/2019
Tương tự có:2020/2019>2021/2020
=>2017/2018+2010/2019<2018/2019+2021/2020
so sánh P=2019/2020+2020/2021+2021/2022 và Q=2019+2020+2021/2020+2021+2022
2+3-4+5+6-7+8+9-10+...+2015+2016-2017+2018+2019-2020+2021+2022
So sánh 2018/2019 + 2019/2020 + 2020/2021:3
Bằng nhau
Ht cho mik
tính
2011 + 2012 + 2013 + 2014 + 2015 + 2016 + 2017 + 2018 + 2019+ 2020 + 2021 +2022 +2023
2011+2012+2013+2014+2015+2016+2017+2018+2019+2020+2021+ 2022+2023 =(2011+2023)+(2013+2022)+...+(2016+2018)+2017 =4034+4034+4034+4034+4034+4034+2017 =4034x6+2017=26221
2011+2012+2013+2014+2015+2016+2017+2018+2019+2020+2021+2022+2023
=(2011+2023)+(2013+2022)+...+(2016+2018)+2017 =4034+4034+4034+4034+4034+4034+2017 =4034x6+2017=26221
so sánh: 2018^2019+1/2018^2020+1 và 2018^2020+1/2018^2021+1
2018^2019+1/2018^2020+1 bé hơn 2018^2020+1/2018^2021+1
2021/2018 x 2022 ... ... ... 2019/2020 x 2020