Math Is Fun Forum

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Inequality

I was not trying to pose a tough question for him. He asked for a couple of problems. I gave him problems that illustrate the method. I did not claim that it was the best method or the only method for those problems. And again, he had no choice.

It was not a race to find the shortest 1 line proof possible.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

sameer mishra

Member

Registered: 2010-08-27

Posts: 64

Re: Inequality

my friend i check ans is squt5
this is "AIEEE" 2007 question

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Inequality

I am sorry, but the answer is not the √5

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

sameer mishra

Member

Registered: 2010-08-27

Posts: 64

Re: Inequality

squt(5) is ans of max(x+2y)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Inequality

Are not we talking about this one?

Maximize 3x - y - 3z Subject to:

He got the right answer too. So why is yours an improvement over his?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

sameer mishra

Member

Registered: 2010-08-27

Posts: 64

Re: Inequality

squt(24) is answer of  max(3x-y-3z)
both are true I check your lagrange multiplier method

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Inequality

Okay, but it is not my method, otherwise it would be called the Method of bobbym Multipliers. I mean I would like that better but do you think we could get the rest of the math community to buy that?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

sameer mishra

Member

Registered: 2010-08-27

Posts: 64

Re: Inequality

what is natural log of squt(-1)
if know  then reply please

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Inequality

Hi sameer;

And please let us keep this thread for the discussion of inequalities, not for attempts to prove I am a dummy.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

123ronnie321

Member

Registered: 2010-09-28

Posts: 128

Re: Inequality

Hi Sameer,
Bobby was just teaching me a new optimisation tool called the Method of Lagrangian Multipliers.

Your method is also good.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Inequality

Hi;

I do not think the concept of using this "method" is seeping into his mind.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

sameer mishra

Member

Registered: 2010-08-27

Posts: 64

Re: Inequality

hello friend.........
find max,min (3x+2y+5z)
if[x^2+y^2+z^2]=45

Last edited by sameer mishra (2010-12-09 18:29:36)

sameer mishra

Member

Registered: 2010-08-27

Posts: 64

Re: Inequality

if x,y,z  are sides of a triangle R is radius of circumcircle A is area of triangle
then prove that
                           log(A)+log(4)+log(R)>=3(log(x)*log(y)*log(z))^1/3

sameer mishra

Member

Registered: 2010-08-27

Posts: 64

Re: Inequality

what is maximum $minimum valu of 1/(3-5cosx)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Inequality

If you want to pose problems put them in the Exercises thread. Learn how to start a new thread or ask and I will show you.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

123ronnie321

Member

Registered: 2010-09-28

Posts: 128

Re: Inequality

sameer mishra

Member

Registered: 2010-08-27

Posts: 64

Re: Inequality

sorry friend  in 1/(3-5cosx) you are wrong

CORRECT ANS
the denominator 3-5cosx=0 ->cosx=3/5 which is in the region [-1 1]
hence correct range is(-∞ -1/2]U [1/8 ∞)
hence you can see wht is max$min

sameer mishra

Member

Registered: 2010-08-27

Posts: 64

Re: Inequality

max$min(3x+2y+5z)
Let  ->
      A=Xi+Yj+Zk
     B=3i+2j+5k
    A.B=mod(A)mod(B) cos (t) "max if cos(t)=1,min if cos(t)=-1"
   3x+2y+5z=squrt(x^2+y^2+z^2)*squrt(38) cos(t)
                  put valu of x^2+y^2+z^2=45 $get ans

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Inequality

Hi;

All that up there is very hard to read. There are a couple of syntax errors. You have forgotten commas and what is $?. Also you have no answers that I can see.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.