diff --git a/book/modules/module3.tex b/book/modules/module3.tex index 520f600..d480261 100644 --- a/book/modules/module3.tex +++ b/book/modules/module3.tex @@ -83,9 +83,10 @@ We can solve this equation for $\alpha$ and $\beta$ by considering the equations arising from the first and second coordinates. Namely, - \[ - \sysdelim..\systeme*{x=\alpha+\beta, y=\alpha-2\beta} - \] +\begin{align*} + x &= \alpha + \beta \\ + y &= \alpha - 2\beta +\end{align*} Subtracting the second equation from the first, we get $x-y=3\beta$ and so $\beta=(x-y)/3$. Plugging $\beta$ into the first equation and solving, we get $\alpha=(2x+y)/3$. Thus, equation \eqref{EQSPAN1} \emph{always} has the solution @@ -113,9 +114,10 @@ We need to determine for which $x$ and $y$ the vector equation $\mat{x\\y} = \alpha\mat{-1\\2}+\beta\mat{1\\-2}$ is consistent. From the first and second coordinates, we get the system - \[ - \sysdelim..\systeme*{x=-\alpha+\beta, y=2\alpha-2\beta}. - \] + \begin{align*} + x &= -\alpha + \beta \\ + y &= 2\alpha - 2\beta. + \end{align*} Adding 2 times the first equation to the second, we get $2x+y=0$ and so $y=-2x$. Therefore, if $\mat{x\\y}$ makes the above system consistent, we must have \[ @@ -143,9 +145,11 @@ $\vec a, \vec b$, and $\vec c$. Reading off the coordinates, we get the system - \[ - \sysdelim..\systeme*{x=\alpha_1+\alpha_3, y=2\alpha_1+\alpha_2+\alpha_3, z=\alpha_1+2\alpha_3}. - \] + \begin{align*} + x &= \alpha_1 + \alpha_3 \\ + y &= 2\alpha_1 + \alpha_2 + \alpha_3 \\ + z &= \alpha_1 + 2\alpha_3. + \end{align*} Solving this system, we see \[ \begin{aligned}