What are the solutions to a set of equations involving triple real numbers and specific conditions?

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In summary, a set of equations involving triple real numbers is a group of mathematical expressions with three variables that can be solved simultaneously to find their values. Specific conditions refer to additional restrictions or requirements that must be met for the equations to be solved. These equations can be solved using various methods and there are specific strategies that can be employed. Solving these equations can be useful in real-world applications and in understanding relationships between variables.
  • #1
anemone
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Here is this week's POTW:

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Determine all triples of real numbers $(a,\,b,\,c)$ such that

$abc=8\\ a^2b+b^2a+c^2a=73\\a(b-c)^2+b(c-a)^2+c(a-b)^2=98$

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  • #2
No one answered last week's POTW. (Sadface) However, you can read the suggested solution below:

Expanding the third equation we get

$a^2b+a^2c+b^2a+b^2c+c^2a+c^2b-6abc=98$

Replace $a^2b+b^2a+c^2a$ by 73 and $abc=8$ into the above equation and rearrange and factorize, we get

$a^2c+b^2v+c^2b=a^2b+b^2a+c^2a\\a^2c+b^2v+c^2b-(a^2b+b^2a+c^2a)=0\\-(a-b)(b-c)(c-a)=0$
Therefore we know that at least two variables are the same.

WLOG, we let $a=c$, the first equation becomes $a^2b=8$ and the second equation becomes $a^2b+ab^2+a^3=73$ and third equation becomes $a(a-b)^2=49$.

Solving this system for $a$ results in

$8+\dfrac{64}{a^3}+a^3=73\\a^6-65a^3+64=0\\(a^3-64)(a^3-1)=0$
$\therefore a=c=1$ or $a=c=4$.

When $a=c=1$, $b=8$ or when $a=c=4$, $b=\dfrac{1}{2}$.

The solutions are hence $(a,\,b,\,c)=(1,\,8,\,1),\,\left(4,\,\dfrac{1}{2},\,4\right)$ and their permutations.
 

Related to What are the solutions to a set of equations involving triple real numbers and specific conditions?

1. What is the definition of a set of equations involving triple real numbers?

A set of equations involving triple real numbers is a group of equations that have three variables, and each variable is a real number. These equations can be solved simultaneously to find the values of the variables that satisfy all the equations.

2. What are the specific conditions that are required for a set of equations involving triple real numbers to have solutions?

The specific conditions required for a set of equations involving triple real numbers to have solutions are that the number of equations must be equal to the number of variables, and the equations must be independent (i.e. not multiples of each other). This ensures that there is enough information to solve for all the variables.

3. How do you solve a set of equations involving triple real numbers?

To solve a set of equations involving triple real numbers, you can use methods such as substitution, elimination, or matrix operations. These methods involve manipulating the equations to eliminate one variable at a time until all the variables have been solved for.

4. Can a set of equations involving triple real numbers have more than one solution?

Yes, a set of equations involving triple real numbers can have more than one solution. This can happen when the equations are not independent, or when there are more variables than equations. In these cases, there may be an infinite number of solutions.

5. Are there any real-life applications of solving sets of equations involving triple real numbers?

Yes, solving sets of equations involving triple real numbers has many real-life applications, such as in physics, engineering, and economics. For example, these equations can be used to model and predict the behavior of systems with three variables, such as the motion of a projectile or the supply and demand of goods.

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