Anyone good at math?

Lt Fresh

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I kept getting my x=3/sqrt(2)=y so my z=1/sqrt(2) which are all close to your answer... off by a few decimals but thats not good enough lol
 

Izuna Uchiha

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I kept getting my x=3/sqrt(2)=y so my z=1/sqrt(2) which are all close to your answer... off by a few decimals but thats not good enough lol
Where do you get that root from O__O? (I mean your general answer).

Post a picture of your work so I can check if there's an error in your work (or in mine if you're correct lol).
 

Izuna Uchiha

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I think I know where you made your error.

When simplifying all the terms at the end when you have only "x's", you did add the nominators and kept it this way:

(18x^2)/9 = 9

So, you ended up with this:

x = (81/18)^(1/2)

Which can be simplified this way:

x = 9/(18)^(1/2) = 9/(2*9)^(1/2) = 9/3*(2)^(1/2) = 3/(2)^(1/2)
 

Izuna Uchiha

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Here is my work
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Ok here's your mistake:

When doing the substitution of your x component into the following equation:

x^2 +y^2 +z^2 = 9

you isolated z in function of x, then you directly used that value (z = (9 - 2x^2)^1/2) and substituted it in that same formula. You can't do that. When you have unknown variables, you need an equal number of equations to find those variables. Let's say you have 2 unknown variables, then you need 2 different equations to find an answer (making a substitutions and isolation one of the variable).

What you did is use 2 equations to find 3 unknown variables (x,y,z). If you had isolated your z component like I did in the Lagrance multiplier derived with respect to z, then your could have easily substituted that value and get a correct answer.

Hope I made myself clear, please ask if you didn't get what I just wrote xd
 

Dragonfly X

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Gosh...smart people...If this was AP or DE english I would be rocking this xd. Math, not my greatest subject :D

On a side note, damn Izuna, you are insanely smart...
 

Izuna Uchiha

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Gosh...smart people...If this was AP or DE english I would be rocking this xd. Math, not my greatest subject :D

On a side note, damn Izuna, you are insanely smart...
Like you just pointed out, we all have our strengths and weaknesses. I couldn't write a good essay even if my life depended on it xd

Intelligence comes in many forms, you developed yours differently, nothing more. There are no greater or better forms of intelligence.
 
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Lt Fresh

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Ooooo I gotcha alright thanks that makes sense where i messed up mhmm. This is the hardest part of the class everything else I understand, Just got to work harder
 

Venus

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I just looked at it and thought if x^2 +y^2 +z^2 = 9

x^2= 2x2
y^2=2x2
z^2=1x1

Then

x^2= 1x1
y^2=2x2
z^2=2x2

and

x^2=2x2
y^2= 1x1
z^2=2x2 Now I look at it and don't know what it even means O_O
 

Izuna Uchiha

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Ooooo I gotcha alright thanks that makes sense where i messed up mhmm. This is the hardest part of the class everything else I understand, Just got to work harder
Really glad I could be of help mate ^^

Again, if you have other problem for me, make a new thread and link me to it, I'll help you!

I just looked at it and thought if x^2 +y^2 +z^2 = 9

x^2= 2x2
y^2=2x2
z^2=1x1

Then

x^2= 1x1
y^2=2x2
z^2=2x2

and

x^2=2x2
y^2= 1x1
z^2=2x2 Now I look at it and don't know what it even means O_O
So you tried to find 1 solution to the equation, but the problem is, there's an infinite number of solutions.

That's why we need the constraint to find the minimum, the maximum and the saddle point (I don't think there's one in that case).

You see, the equation your tried to rationalize is that of a sphere, so there's no way you could find one absolute value out of this xd

Just for the fun of it, here's the two equations combined in a 3d maping:

You must be registered for see images
 

Venus

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Really glad I could be of help mate ^^

Again, if you have other problem for me, make a new thread and link me to it, I'll help you!



So you tried to find 1 solution to the equation, but the problem is, there's an infinite number of solutions.

That's why we need the constraint to find the minimum, the maximum and the saddle point (I don't think there's one in that case).

You see, the equation your tried to rationalize is that of a sphere, so there's no way you could find one absolute value out of this xd

Just for the fun of it, here's the two equations combined in a 3d maping:

You must be registered for see images
xd I just read it once and said what came to my head. What I typed out before is what I saw. I didn't think I'd be able to figure it out without using my head.
Maybe I should come to you for maths lessons, I'm getting a bit rusty. :shy:
 

Izuna Uchiha

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xd I just read it once and said what came to my head. What I typed out before is what I saw. I didn't think I'd be able to figure it out without using my head.
Maybe I should come to you for maths lessons, I'm getting a bit rusty. :shy:
Well if you have interesting problems post them and I'll see what I can do :)
 

Izuna Uchiha

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I'd prefer to watch and learn from you. xd
I'm not a tutor anymore. Above all I wouldn't give classes online, it's too hard to be efficient.

I'll keep myself to help those who struggle with math/physics problem. (Can't promise anything when it comes to university level math/physic considering I'm still there lol).
 
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