Comparing Almost 1s

Algebra Level 1

Which of these numbers is larger?

2016 2015 , 2017 2016 {\dfrac{2016}{2015}}\quad , \quad {\dfrac{2017}{2016}}

2017 2016 \dfrac{2017}{2016} 2016 2015 \dfrac{2016}{2015}

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9 solutions

Nihar Mahajan
Feb 20, 2016

1 2015 > 1 2016 1 + 1 2015 > 1 + 1 2016 2015 2015 + 1 2015 > 2016 2016 + 1 2016 2015 + 1 2015 > 2016 + 1 2016 2016 2015 > 2017 2016 \dfrac{1}{2015} > \dfrac{1}{2016} \\ \Rightarrow 1+\dfrac{1}{2015} > 1+\dfrac{1}{2016} \\ \Rightarrow \dfrac{2015}{2015} + \dfrac{1}{2015} > \dfrac{2016}{2016}+\dfrac{1}{2016} \\ \Rightarrow \dfrac{2015+1}{2015} > \dfrac{2016+1}{2016} \\ \Rightarrow \boxed{\dfrac{2016}{2015} > \dfrac{2017}{2016}}

Moderator note:

Good way to simplify the inequality.

Nicely done!

Sandeep Bhardwaj - 5 years, 3 months ago

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Thank you!

Nihar Mahajan - 5 years, 3 months ago
Harsh Khatri
Feb 20, 2016

For any positive integer n > 1 n>1 consider this:

n 2 > n 2 1 n^2 > n^2-1

n × n > ( n + 1 ) × ( n 1 ) \displaystyle \Rightarrow n\times n> (n+1) \times (n-1)

n n 1 > n + 1 n \displaystyle \Rightarrow \frac{n}{n-1}>\frac{n+1}{n}

Substituting n=2016 :

2016 2015 > 2017 2016 \displaystyle \Rightarrow \boxed{ \frac{2016}{2015} > \frac{2017}{2016}}

(+1).. Did the same way..

Rishabh Jain - 5 years, 3 months ago

Actually, in any real number, it is true - even zero or a negative. Since it is a squared expression, a negative or zero number ,in that expression, when squared, is greater than the right side.

Lance Fernando - 5 years, 3 months ago

Note that n n can be 1.

EDIT: I said that only for the first statement.

Mehul Arora - 5 years, 3 months ago

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n-1 is coming in denominator which restricts n from taking the value 1!!

Rishabh Jain - 5 years, 3 months ago

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No I said that for the first statement

n 2 > n 2 1 n^2 > n^2 -1

Mehul Arora - 5 years, 3 months ago

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@Mehul Arora Get a room guyzz :P very nice explanation though

Aditya Raman - 5 years, 3 months ago

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@Aditya Raman Haha XD !! Thanks!

Harsh Khatri - 5 years, 3 months ago

Don't get me wrong, I accidentally clicked unfollow :P

Mehul Arora - 5 years, 3 months ago

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@Mehul Arora Yeah .. I was terrified- how a person could follow someone twice!! ...
Anyways its irrelevant but why you dislike WWE .... (If you could answer, no force from my side)..

Rishabh Jain - 5 years, 3 months ago

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@Rishabh Jain

  1. It's unreal. Really unreal.

  • What's the point of seeing two random people beat each other up?

  • The signature moves and stuff are lame. Kids try to copy it all the time, and it is lame as anything.

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  • P.S. How are you always online?

    Mehul Arora - 5 years, 3 months ago

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    @Mehul Arora I use android for surfing brilliant and always receive a notification from my mail id when someone replies.... Anyways (+1) for a nice explanation.. ;-)

    Rishabh Jain - 5 years, 3 months ago

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    @Rishabh Jain Hehe thanks :)

    Mehul Arora - 5 years, 3 months ago
    Rohit Udaiwal
    Feb 20, 2016

    \begin{aligned} \color{#3D99F6}{\dfrac {1}{2015}} \quad \boxed {>}& \quad \color{#D61F06}{\dfrac {1}{2016}} \\ \color{#3D99F6}{\dfrac {1}{2015}+1} \quad \boxed {>}& \quad \color{#D61F06}{\dfrac {1}{2016}+1} \\\\ \therefore \color{#3D99F6}{\dfrac{2016}{2015}}\quad \boxed {>}& \quad \color{#D61F06}{\dfrac{2017}{2016}} \end{aligned} \end {equation}

    Roger Erisman
    Feb 2, 2017

    To compare fractions: A/B versus C/D

    Cross multiply: A D and B C

    Larger value is the side where the larger fraction is.

    2016X2016 = 4064256 and 2015X2017 = 4064255

    so 2016/2015 is larger

    Hung Woei Neoh
    Apr 14, 2016

    Let n = 2015 , n + 1 = 2016 , n + 2 = 2017 n = 2015, n+1 = 2016, n+2 = 2017

    2016 2015 \dfrac{2016}{2015}

    = n + 1 n =\dfrac{n+1}{n}

    = n n + 1 n =\dfrac{n}{n} +\dfrac{1}{n}

    = 1 + 1 n =1 + \dfrac{1}{n}

    2017 2016 \dfrac{2017}{2016}

    = n + 2 n + 1 =\dfrac{n+2}{n+1}

    = n + 1 n + 1 + 1 n + 1 =\dfrac{n+1}{n+1} +\dfrac{1}{n+1}

    = 1 + 1 n + 1 =1 + \dfrac{1}{n+1}

    Now, we know that:

    n < n + 1 n<n+1

    1 n > 1 n + 1 \dfrac{1}{n}>\dfrac{1}{n+1}

    1 + 1 n > 1 + 1 n + 1 1+ \dfrac{1}{n}>1+\dfrac{1}{n+1}

    Therefore, the general rule for these kind of fractions is:

    n + 1 n > n + 2 n + 1 \boxed{\dfrac{n+1}{n} > \dfrac{n+2}{n+1}}

    For our specific case here:

    2016 2015 > 2017 2016 \boxed{\dfrac{2016}{2015}>\dfrac{2017}{2016}}

    Note: The general rule also works for negative numbers. Test it out!

    Note note: This general rule does not work for n = 0 n=0 or n = 1 n=-1

    Consider a function x+1/x it is a decreasing function as its derivative is negative for all real x so lower value of x higher the value of function

    Amed Lolo
    Feb 29, 2016

    (2016\2015)÷(2017\2016)=2016^2÷{2015×2017)=2.016^2÷{2.015×2.017}. (2+.016)^2=4+.064+.000256={4.064256} (2+.015)×(2+.017)=4+.034+.030+.000255. ={4.064255} so {2016 ÷2015}÷{2017÷2016}>1 so (2016÷2015)>(2017÷2016)####

    Jack Rawlin
    Feb 29, 2016

    2016 2015 ? 2017 2016 \frac{2016}{2015} ~?~ \frac{2017}{2016}

    1 + 1 2015 ? 1 + 1 2016 1 + \frac{1}{2015} ~?~ 1 + \frac{1}{2016}

    1 2015 ? 1 2016 \frac{1}{2015} ~?~ \frac{1}{2016}

    1 ? 2015 2016 1 ~?~ \frac{2015}{2016}

    1 > 2015 2016 1 > \frac{2015}{2016}

    1 2015 > 1 2016 \frac{1}{2015} > \frac{1}{2016}

    1 + 1 2015 > 1 + 1 2016 1 + \frac{1}{2015} > 1 + \frac{1}{2016}

    2016 2015 > 2017 2016 \large \boxed{\frac{2016}{2015} > \frac{2017}{2016}}

    Aditya Jain
    Feb 20, 2016

    If a>b>c then, (b/c)>(a/b) Here, a =2017 & b=2016 & c = 2015

    if a > b > c a>b>c

    you say b c > a b \dfrac {b}{c} > \dfrac {a}{b}

    let a = 6 , b = 2 , c = 1 a=6 , b=2 , c=1 and substitute:

    2 1 > 6 2 = 3 \dfrac {2}{1} > \dfrac {6}{2}=3

    the inequality wrong.

    Nxin Nasn - 5 years, 3 months ago

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