Simple Simultaneous equation help

  • MHB
  • Thread starter nacho-man
  • Start date
In summary, $x^* = (\sqrt{w_2 \bar{y}/w_1}, \sqrt{w_1\bar{y}/w_2})$ is the correct solution for $x^*$, with $\lambda^* = \sqrt{\frac{w_1w_2}{\bar y}}$. The mistake was made in not including the square root signs in the first solution for $x^*$.
  • #1
nacho-man
171
0
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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  • #2
anyone? :(

If I wasn't clear, $x^* = (x_1,x_2)$
 
  • #3
Hi nacho,

The square root signs are missing in the answer for $x^*$. It should be $x^* = (\sqrt{w_2 \bar{y}/w_1}, \sqrt{w_1\bar{y}/w_2})$.
 
  • #4
this was a suspicion of mine - thank you!
 

FAQ: Simple Simultaneous equation help

What are simultaneous equations?

Simultaneous equations are a set of two or more equations with multiple variables that are solved at the same time to find a common solution.

What is the purpose of solving simultaneous equations?

Solving simultaneous equations can help determine the point of intersection between two or more lines, which can be useful in various real-life scenarios such as finding the break-even point in business or the optimal solution in engineering problems.

How do you solve simultaneous equations?

There are several methods for solving simultaneous equations, including substitution, elimination, and graphing. The method used depends on the specific equations and variables involved.

What are the common mistakes to avoid when solving simultaneous equations?

Some common mistakes to avoid when solving simultaneous equations include not distributing negative signs correctly, forgetting to combine like terms, and making calculation errors. It is also important to double-check the final solution by substituting it back into the original equations.

Can simultaneous equations have more than two variables?

Yes, simultaneous equations can have any number of variables. However, the number of equations must be equal to the number of variables in order to solve for a unique solution.

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