\(\frac{a}{b}\)và \(\frac{a+2016}{b+2016}\)(vớ...">
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5 tháng 7 2019

Ta có : \(A=\frac{2016^{2016}+2}{2016^{2016}-1}=\frac{2016^{2016}-1+3}{2016^{2016}-1}=1+\frac{3}{2016^{2016}-1}\)

           \(B=\frac{2016^{2016}}{2016^{2016}-3}=\frac{2016^{2016}-3+3}{2016^{2016}-3}=1+\frac{3}{2016^{2016}-3}\)

Vì \(\frac{3}{2016^{2016}-1}>\frac{3}{2016^{2016}-3}\)

\(\Rightarrow1+\frac{3}{2016^{2016}-1}>1+\frac{3}{2016^{2016}-3}\)

\(\Rightarrow A>B\)

\(a>b\Rightarrow a+2016>b+2016\)

\(\Rightarrow\frac{a}{b}=\frac{b+a-b}{b}\)

\(\Rightarrow\frac{a+2016}{b+2016}=\frac{b+2016+a+2016-b+2016}{b+2016}=\frac{b+a-a}{b+2016}\)

Vì: \(\frac{b+a-a}{b}>\frac{b+a-b}{b+2016}\)

\(\Rightarrow\frac{a}{b}>\frac{a+2016}{b+2016}\)

7 tháng 7 2016

Ta có:

  • \(\frac{a}{b}=\frac{a\left(b+2016\right)}{b\left(b+2016\right)}\)

               \(=\frac{ab+2016a}{b\left(b+2016\right)}\)

  • \(\frac{a+2016}{b+2016}=\frac{b\left(a+2016\right)}{b\left(b+2016\right)}\)

                             \(=\frac{ab+2016b}{b\left(b+2016\right)}\)

Vì \(a>b\Rightarrow2016a>2016b\)

\(\Rightarrow ab+2016a>ab+2016b\)

\(\Rightarrow\frac{ab+2016a}{b\left(b+2016\right)}>\frac{ab+2016b}{b\left(b+2016\right)}\)

\(\Rightarrow\frac{a}{b}>\frac{a+2016}{b+2016}\)

20 tháng 6 2018

a) ta có: \(1-\frac{2016}{2017}=\frac{1}{2017}\)

\(1-\frac{2017}{2018}=\frac{1}{2018}\)

\(\Rightarrow\frac{1}{2017}>\frac{1}{2018}\Rightarrow1-\frac{2016}{2017}>1-\frac{2017}{2018}\Rightarrow\frac{2016}{2017}< \frac{2017}{2018}\)

b) ta có: \(\frac{2017}{2016}-1=\frac{1}{2016};\frac{2018}{2017}-1=\frac{1}{2017}\)

\(\Rightarrow\frac{1}{2016}>\frac{1}{2017}\Rightarrow\frac{2017}{2016}-1>\frac{2018}{2017}-1\Rightarrow\frac{2017}{2016}>\frac{2018}{2017}\)

20 tháng 6 2018

Tru 1 moi phan so roi so sanh nha 'O_O"

24 tháng 8 2016

+\(\frac{a}{b}=1\Leftrightarrow a=b\Leftrightarrow\frac{a}{b}=\frac{a+2016}{b+2016}\)

+\(\frac{a}{b}>1\Leftrightarrow a>b\Leftrightarrow\frac{a}{b}-1=\frac{a-b}{b}>\frac{a-b}{b+2016}=\frac{a+2016}{b+2016}-1\)=> \(\frac{a}{b}>\frac{a+2016}{b+2016}\)

+\(\frac{a}{b}< 1\Leftrightarrow a< b\Leftrightarrow1-\frac{a}{b}=\frac{b-a}{b}>\frac{b-a}{b+2016}=1-\frac{a+2016}{b+2016}\)=>\(\frac{a}{b}< \frac{a+2016}{b+2016}\)

23 tháng 8 2016

A+2016/B+2016=A/B+2016/2016=A/B+1

=)A/B<A/B+1

=)A/B<A+2016/B+2016

23 tháng 8 2016

\(\frac{a}{b}\)<\(\frac{a+2016}{b+2016}\)

21 tháng 10 2016

Có: \(\sqrt{2015}< \sqrt{2016}\)

=>\(\frac{1}{\sqrt{2015}}>\frac{1}{\sqrt{2016}}\)

=>\(\frac{1}{\sqrt{2015}}-\frac{1}{\sqrt{2016}}>0\)

=>\(\sqrt{2015}+\sqrt{2016}+\frac{1}{\sqrt{2015}}-\frac{1}{\sqrt{2016}}>\sqrt{2015}+\sqrt{2016}\)

=>\(\left(\sqrt{2015}+\frac{1}{\sqrt{2015}}\right)+\left(\sqrt{2016}-\frac{1}{\sqrt{2016}}\right)>\sqrt{2015}+\sqrt{2016}\)

=>\(\frac{2016}{\sqrt{2015}}+\frac{2015}{\sqrt{2016}}>\sqrt{2015}+\sqrt{2016}\)

13 tháng 6 2016

Ta có:

\(\frac{a}{b}\)\(\frac{a\left(b+2016\right)}{b\left(b+2016\right)}\)=\(\frac{ab+2016a}{b\left(b+2016\right)}\)

\(\frac{a+2016}{b+2016}\)=\(\frac{\left(a+2016\right)b}{\left(b+2016\right)b}\)=\(\frac{ab+2016b}{b\left(b+2016\right)}\)

Vì b > 0 nên mẫu số của hai phân số trên dương. Ta so sánh tử số.

* Nếu a < b => ab+2016a < ab+2016b

=> \(\frac{a}{b}\)<\(\frac{a+2016}{b+2016}\)

* Nếu a = b => ab+2016a = ab+2016b

=> \(\frac{a}{b}\)=\(\frac{a+2016}{b+2016}\)

* Nếu a > b => ab+2016a > ab+2016b

=> \(\frac{a}{b}\)>\(\frac{a+2016}{b+2016}\)

13 tháng 6 2016

Giả sử a/b = 1/3 còn phân số kia là 2017/2019

quy đồng 1/3 = 2017/6051

Vì 6051>2019 nên 2017/2019 > 2017/6051 và 2017/2019>1/3

Vậy \(\frac{a}{b}< \frac{a+2016}{b+2016}\)