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#101 Re: Help Me ! » Inequality » 2010-12-05 05:36:24

I have never heard of lagrangian multipliers. Can you post a link where i can learn the basics of it?

#102 Re: Help Me ! » Inequality » 2010-12-05 00:10:02

You are right.
I did it using am gm inequality. Thanks for your time.

#103 Re: Help Me ! » Inequality » 2010-12-04 23:21:57

I know that but how did you get the answer?

Yes, you have read the question right.

#104 Help Me ! » Inequality » 2010-12-04 23:03:45

123ronnie321
Replies: 43

x,y,z>0 and are real and satisfy x + y + z = 1

Find minimum value of {(1/x)+1}{(1/y)+1}{(1/z)+1}.

#107 Re: Maths Is Fun - Suggestions and Comments » College Algebra - Volunteers Wanted » 2010-12-03 22:50:43

College Algebra is very nice and helpful.!!!

Can you write a similar article on vector algebra?

#108 Re: Help Me ! » Geometry » 2010-12-02 01:47:04

The longest side will be the hypotenuse.
Use the Pythagoras theorem to find the other side.....

This link will help you understand the basics of a triangle.
http://www.mathsisfun.com/triangle.html

#109 Re: Help Me ! » Calculus: Limit » 2010-11-30 22:53:45

you are right. the limit does not exist.
draw a graph of (x-2)/(x-1) and you will know better.

#111 Re: Introductions » Hi everyone » 2010-11-21 21:55:36

Thanks bobby. Yes, I will never give up on my guitar.

I have been here for over a month now and it feels good to have distant yet close friends.

Bobby, are you a student? professor? ???

#112 Re: This is Cool » Geometry problem » 2010-11-21 04:51:33

I am using your figure to solve this.

let the midpoint of PR be M
Let OQ = t < 2a
Let PQ = k.

GeometryProblem.png

PQ = P`Q` = k = 2P'M
PR = OQ = t = 2PM
PM^2 + P`M^2 = P`P^2 = a^2        ...  Pythagoras theorem

therefore, k^2 + t^2 = (2a)^2. which is a circle if we make the following assumptions-
Let OQ act like x axis  and and OR as Y axis.
Co ordinates of pt P are k,t.

#113 Introductions » Hi everyone » 2010-11-21 04:13:50

123ronnie321
Replies: 8

Hi

I am an 18 year old Indian student.
I am an IIT aspirant and that is why i have joined this website - to improve my maths and learn some lessons of life.
I also like Physics and i love playing my guitar.

#114 Re: Help Me ! » Co-ordinate Geometry » 2010-11-21 03:55:50

Ok,

bob and sameer,

to be honest i am not fully satisfied with either of your answers although they are correct. I think i should be more clear with what i am asking.

Can you say which one is obtuse angle bisector and which one acute just by putting some conditions on a,b,c,p,q,r. Like a computer programme.

If numerical values are given i am able to solve. This is what once our teacher had asked us.

#115 Re: Exercises » Is this cool with you? » 2010-11-21 03:29:40

Hi bobby,

sorry,
The roots of above equation are real and are -2, 1 + sqrrtt(5), 1 - sqrrtt(5).
and they do satisfy the conditions of the problem.

#116 Re: Help Me ! » Co-ordinate Geometry » 2010-11-16 19:27:38

thanks bob

yes, graphical method is the best.

#117 Re: Exercises » Challenge » 2010-11-16 19:25:56

hi bobby

i tried condensing those series and i got the result very similar to what you posted. I must have made some silly error while calculating.
i wrote the series of e^x, e^wx & e^(w^2)x {where w = complex cube root of unity} and added the three......

#118 Help Me ! » Co-ordinate Geometry » 2010-11-15 03:33:21

123ronnie321
Replies: 6

the angle bisector of two lines ax + by + c = 0 & px + qy + r = 0
is the locus of pts whose perpendicular distance from both lines is same.
We write this mathaematically as

|(aX + bY + c)/sqrrt(a^2 + b^2)| = + or - |(pX + qY + r)/sqrrt(p^2 + q^2)|

How do we differentiate between the two???
ie which one is acute angle bisector and which one is obtuse????

#120 Exercises » Challenge » 2010-11-13 01:41:55

123ronnie321
Replies: 7

All u hv to do is find functions satisfying -

f` = g
g`= h
h`= f

f,g,h are different functions.
where f means f(x) and f` means f`(x)


-------
A simpler version -

f` = g
g`= f

f(0) = 1
g(0) = 0
find f(1)

#121 Help Me ! » Trigonometry » 2010-10-17 03:00:20

123ronnie321
Replies: 2

sin(a) + sin(a+b) + sin(a+2b) +.....+ sin (a+nb) = ???

#122 Re: Exercises » Daniel's Challenge Thread » 2010-09-28 08:05:47

JaneFairfax wrote:

New challenge:

smile

All we hv to do is to prove that 9k^2 - 1 is divisible by 8.
=(3k+1)(3k-1) this reduces down to your other question -- product of 2 consecutive even nos is div by 8.......

#123 Re: Exercises » Integral and inequality » 2010-09-28 07:41:17

bobbym wrote:

Hi;

Evaluate this integral:

Prove the inequality:

1/2[x - log(sinx + cosx)]

#124 Re: Exercises » Integral and inequality » 2010-09-28 07:36:42

bobbym wrote:

Hi;

Another integral this one is also easy:

(e^2x)/2 - (e^-2x)/2

#125 Re: Exercises » Integration by Substitution » 2010-09-28 07:13:18

bobbym wrote:

Hi;

Here is an interesting integral done by substitution.

Ans - 0

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