Skip to main content
\(\renewcommand{\chaptername}{Unit} \newcommand{\derivativehomeworklink}[1]{\href{http://db.tt/cSeKG8XO}{#1}} \newcommand{\chpname}{unit} \newcommand{\sageurlforcurvature}{http://bmw.byuimath.com/dokuwiki/doku.php?id=curvature_calculator} \newcommand{\uday}{ \LARGE Day \theunitday \normalsize \flushleft \stepcounter{unitday} } \newcommand{\sageworkurl}{http://bmw.byuimath.com/dokuwiki/doku.php?id=work_calculator} \newcommand{\sagefluxurl}{http://bmw.byuimath.com/dokuwiki/doku.php?id=flux_calculator} \newcommand{\sageworkfluxurl}{http://bmw.byuimath.com/dokuwiki/doku.php?id=both_flux_and_work} \newcommand{\sagelineintegral}{http://bmw.byuimath.com/dokuwiki/doku.php?id=line_integral_calculator} \newcommand{\sagephysicalpropertiestwod}{http://bmw.byuimath.com/dokuwiki/doku.php?id=physical_properties_in_2d} \newcommand{\sagephysicalpropertiesthreed}{http://bmw.byuimath.com/dokuwiki/doku.php?id=physical_properties_in_3d} \newcommand{\sageDoubleIntegralCheckerURL}{http://bmw.byuimath.com/dokuwiki/doku.php?id=double_integral_calculator} \newcommand{\myscale}{1} \newcommand{\ds}{\displaystyle} \newcommand{\dfdx}[1]{\frac{d#1}{dx}} \newcommand{\ddx}{\frac{d}{dx}} \newcommand{\ii}{\vec \imath} \newcommand{\jj}{\vec \jmath} \newcommand{\kk}{\vec k} \newcommand{\vv}{\mathbf{v}} \newcommand{\RR}{\mathbb{R}} \newcommand{\R}{ \mathbb{R}} \newcommand{\inv}{^{-1}} \newcommand{\im}{\text{im }} \newcommand{\colvec}[1]{\begin{bmatrix}#1\end{bmatrix} } \newcommand{\cl}[1]{ \begin{matrix} #1 \end{matrix} } \newcommand{\bm}[1]{ \begin{bmatrix} #1 \end{bmatrix} } \DeclareMathOperator{\rank}{rank} \DeclareMathOperator{\rref}{rref} \DeclareMathOperator{\vspan}{span} \DeclareMathOperator{\trace}{tr} \DeclareMathOperator{\proj}{proj} \DeclareMathOperator{\curl}{curl} \newcommand{\blank}[1]{[14pt]{\rule{#1}{1pt}}} \newcommand{\vp}{^{\,\prime}} \newcommand{\lt}{<} \newcommand{\gt}{>} \newcommand{\amp}{&} \)

Section1.3Solving Systems of equations

Exercise1.3.1

Solve the following linear systems of equations.

For additional practice, make up your own systems of equations. Use \wolfA  or the SageCell below to check your work.

(a)

\(\begin{cases}x+y\amp =3\\2x-y\amp =4 \end{cases}\)

(b)

\(\begin{cases}-x + 4y\amp =8\\3x - 12y\amp =2 \end{cases}\)

Exercise1.3.2

Find all solutions to the linear system \(\begin{cases}x+y+z\amp =3\\2x-y\amp =4 \end{cases}\text{.}\) Since there are more variables than equations, this suggests there is probably not just one solution, but perhaps infinitely many. One common way to deal with solving such a system is to let one variable equal \(t\text{,}\) and then solve for the other variables in terms of \(t\text{.}\) Do this three different ways.

This link will show you how to specify which variable is \(t\) when using Wolfram Alpha.

(a)

If you let \(x=t\text{,}\) what are \(y\) and \(z\text{.}\) Write your solution in the form \((x,y,z)\) where you replace \(x\text{,}\) \(y\text{,}\) and \(z\) with what they are in terms of \(t\text{.}\)

(b)

If you let \(y=t\text{,}\) what are \(x\) and \(z\) (in terms of \(t\)).

(c)

If you let \(z=t\text{,}\) what are \(x\) and \(y\text{.}\)