Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
\(\frac{2015}{2016}+\frac{2016}{2017}>\frac{\left(2015+2016\right)}{\left(2016+2017\right)}=\frac{2015}{2016+2017}+\frac{2016}{2016+2017}\)
Cho A= 2015/2016+2016/2017;B=2015+2016/2016+2017.Không quy đồng hãy so sánh A và B
\(\frac{2015}{2016}\) > \(\frac{2015}{2016+2017}\)
\(\frac{2016}{2017}\) > \(\frac{2016}{2016+2017}\)
Cộng vế với vế ta có:
A = 2015/2016 + 2016/2017 > \(\frac{2015+2016}{2016+2017}\)
- \(A=\frac{2015}{2016}+\frac{2016}{2017}>1;\)
- \(B=\frac{2015+2016}{2016+2017}< 1\)
- Nên A>B
A=2015/2016+2016/2017+2017/2018>2015/2018+2016/2018+2017/2018
=6048/2018>1
B=2015+2016+2017/2016+2017+2018=6048/6051<1
=>A>B
Có: B = 2015 + 2016 + 2017/2016 + 2017 + 2018
B= 2015 / (2015 + 2016+2017) + 2016/(2016+2017+2018) + 2017/(2016 + 2017 + 2018)
vì 2015/2016 > 2015/(2016 + 2017+2018) ; 2016/2017>2016/(2016+2017+2018) ; 2017/2018 > 2017/(2016+2017+2018)
=> A>B
Ta có:2015/2016>2015/2016+2017+2018
2016/2017>2016/2016+2017+2018
2017/2018>2017/2016+2017+2018-Mình áp dụng so sánh phân số cùng tử đấy.
Suy ra2015/2016+2016/2017+2017/2018>(2015+2016+2017)/(2016+2017+2018)=B
\(A=\frac{2015}{2016}+\frac{2016}{2017}=1-\frac{1}{2016}+1-\frac{1}{2017}>1\)
\(B=\frac{2015+2016}{2016+2017}< \frac{2016+2017}{2016+2017}=1\)
Suy ra \(A>B\).
có cách nhanh hơn
\(A=\frac{2015}{2016}+\frac{2016}{2017}\)
\(=1-\frac{1}{2015}+1-\frac{1}{2016}\)
\(=2-\left(\frac{1}{2015}+\frac{1}{2016}\right)>1\)
\(B=\frac{2015+2016}{2016+2017}\)
\(=\frac{4031}{4033}\)
\(=1-\frac{2}{4033}< 1\)
Vậy A > B
Ta có :
\(A=\frac{2015}{2016}+\frac{2016}{2017}=1-\frac{1}{2016}+1-\frac{1}{2017}=2-\left(\frac{1}{2016}+\frac{1}{2017}\right)\) \(\Rightarrow\)\(A>1\)
\(B=\frac{2015+2016}{2016+2017}< \frac{2016+2017}{2016+2017}=1\)\(\Rightarrow\)\(B< 1\)
Từ đó ta so sánh được \(A>B\)