#[Examples][Ejemplos]#
1. #[The reduced matrix][La matiz reducida]#
#[represents the system of equations][representa el sistema de ecuaciones]#
\\ $x = 9$
\\ $y = -6$,
#[and so a unique solution][y así una solución]# $(x, y) = (9, -6)$.
2. #[The matrix][La matiz]#
#[represents the system of equations][representa el sistema de ecuaciones]#
\\ $x - 3y = 4$
\\ $0 = 0$.
#[Ignoring the second equation (which tells us nothing interesting) and solving the first equation for $x$ gives][Ignorando la segunda ecuación (que no nos dice nada interesante), obtenemos, resolviendo $x$ en la primera ecuación nos da]#
\\ $x = 3y + 4$.
This tells us that, so long as $x$ satisfies this equation, the system of equations is satisfied regardless of the value of $y$; for instance, if we choose $y = 100$ we get $x = 3(100)+4 = 304$, and therefore the solution $(x, y) = (304, 100)$. But this is only one
particular solution. We can get other particular solutions by choosing other values for $y$, such as $y = 0$, which gives us another particular solution: $(x, y) = (4, 0)$.
To represent all possible solutions, we don't specify any particular value for $y$, and just write
\\ $(x,y) = (3y + 4, y); \ y \text{ arbitrary } $ \t \gap[10]
#[This is called the
general solution because every particular solution can be obtained from the general solution by choosing a value for the arbitrary varaiable $y$. For instance, choosing $y=-1$ gives us a
particular solution][Esto se denomina
solución general porque cualquier solución particular se puede obtener a partir de la solución general eligiendo un valor para la variable arbitraria $y$. Por ejemplo, si elegimos $y=-1$, obtenemos una
solución particular.]#
\\ $(x,y) = (1, -1); $ \t \gap[10]
#[Alternative way to write the general solution][Una manera alternativa escribir la solución general.]#
#[We can get another way of writing the general solution by solving for $y$ instead of $x$][]#
\\ $y = \dfrac{1}{3}(x-4)$
#[where this time $x$ is arbitrary][donde esta vez $x$ es arbitraria]#:
\\ $(x,y) = \left(x,\dfrac{1}{3}(x-4)\right); \x \text{ arbitrary } $ \t