12-10-09 Greatest Integer.

This one is relatively simpler compared to the other question we have solved..

\left[\frac{n}{3}\right]+\left[\frac{n+2}{6}\right]+\left[\frac{n+4}{6}\right]=\left[\frac{n}{2}\right]+\left[\frac{n+3}{6} \right]

10 Answers

1
Philip Calvert ·

LHS \ :\ \left[\frac{n}{3} \right]+\left[\frac{n}{6}+\frac{1}{3}\right]+\left[\frac{n}{6}+\frac{2}{3}\right]=\left[\frac{n}{3} \right]+\left[\frac{n}{2} \right]-\left[\frac{n}{6} \right]
R.H.S. \ :\ \left[\frac{n}{2} \right]+\left[\frac{n}{6}+\frac{1}{2} \right]=\left[\frac{n}{2} \right]+ \left[\frac{n}{3} \right]-\left[\frac{n}{6}\right]

used this one :
http://targetiit.com/iit-jee-forum/posts/10-09-09-greatest-integer-function-11066.html

1
Philip Calvert ·

something more aesthetic maybe [12]

1
Unicorn--- Extinct!! ·

[7]
Do we have to prove it??Philip has already done that

3
iitimcomin ·

philip ... ur signature was stated by rutherford na!!!!!!!!!!![3]

62
Lokesh Verma ·

I am giving a "pink slip" but the fact is that it is much simpler...

I mean this one can be solved by simply taking n between "" and "' and then showing that it holds for the rest..

Use the idea that prophet sir gave in that question..

1
Philip Calvert ·

okie.

Let\ F(n)=\left[\frac{n}{3}\right]+\left[\frac{n+2}{6}\right]+\left[\frac{n+4}{6}\right]-\left[\frac{n}{2}\right]-\left[\frac{n+3}{6} \right]

Now\ we\ note\ that\ F(n)=F(n+6).

1
Unicorn--- Extinct!! ·

@ Philip- F(n) mein kuch problem lag rahi hai...[1]

1
Philip Calvert ·

Now it is ok.
thanks for the correction.
Actually I copied the url from nishant bhaiyya's post and edited it directly, so missed out the other sign.

1
Unicorn--- Extinct!! ·

[4]
Another bookmark...

3
msp ·

sir i din see the previous discussion,on seeing the question i think it can be proved if we take two cases if n is a multiple of 6 and it is not.so we can do the rest part of the soln,though it is not elegant method of solving,i felt this is the easiest soln.

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