Simple Simultaneous equation help

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Discussion Overview

The discussion revolves around solving a set of simultaneous equations involving variables \(x_1\), \(x_2\), and a parameter \(\lambda\). The context includes exploring the derivation of solutions for these variables under certain conditions, specifically focusing on the equations provided and the relationships between the variables.

Discussion Character

  • Homework-related, Mathematical reasoning

Main Points Raised

  • One participant presents a set of equations and claims to have derived a solution for \(\lambda^*\) but struggles to obtain the solution for \(x^*\).
  • The participant attempts to substitute expressions for \(x_1\) and \(x_2\) into the third equation but encounters difficulties in reaching the desired form.
  • Another participant corrects the expression for \(x^*\), suggesting that it should include square root signs, specifically stating \(x^* = (\sqrt{w_2 \bar{y}/w_1}, \sqrt{w_1\bar{y}/w_2})\).
  • The original poster expresses gratitude for the correction, indicating a collaborative effort to clarify the solution.

Areas of Agreement / Disagreement

There is no consensus on the derivation of \(x^*\) as the original poster was unable to reach the corrected form without assistance. The discussion includes a correction but does not resolve the underlying challenges faced in the derivation process.

Contextual Notes

The discussion does not clarify the assumptions or dependencies that may affect the derivation of the solutions, nor does it address any potential limitations in the equations provided.

nacho-man
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Assuming $x_1, x_2 \geq 0, \lambda \neq 0, w_1,w_2 > 0$

We have the equalities:

$$w_1 - \lambda x_2 = 0 ... (1)$$
$$w_2 - \lambda x_1 = 0 ... (2)$$
$$\bar y - x_1x_2= 0 ... (3)$$

My solutions say that $\lambda^* = \sqrt\frac{w_1w_2}{\bar y}$
Which I was able to solve myself.

The other solution is $x^* = (\frac{w_2 \bar y}{w_1}, \frac{w_1 \bar y}{w_2})$

Which I cannot seem to get. Would anyone be so kind as to point out how to obtain solutions for $x^*$ ?

I tried:

$x_1= \frac{w_2}{\lambda}$ and $x_2 = \frac{w_1}{\lambda}$

then put these into the 3rd equation, but ended up gettig
$\bar y = \frac{w_1w_2}{\lambda^2}$ which I couldn't see turning into what I needed either way - even just subbing in one of the x-values at a time, but to no avail.
 
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anyone? :(

If I wasn't clear, $x^* = (x_1,x_2)$
 
Hi nacho,

The square root signs are missing in the answer for $x^*$. It should be $x^* = (\sqrt{w_2 \bar{y}/w_1}, \sqrt{w_1\bar{y}/w_2})$.
 
this was a suspicion of mine - thank you!
 

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