## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$\text{Set Builder Notation: } \{t|t\gt -5\} \\\text{Interval Notation: } (-5,\infty)$
$\bf{\text{Solution Outline:}}$ Use the properties of inequality to solve the given inequality, $4\lt t+9 .$ Write the answer in both set-builder notation and interval notation. Finally, graph the solution set. In the graph, a hollowed dot is used for $\lt$ or $\gt.$ A solid dot is used for $\le$ or $\ge.$ $\bf{\text{Solution Details:}}$ Using the properties of inequality, the given equation is equivalent to \begin{array}{l}\require{cancel} 4\lt t+9 \\\\ -t\lt 9-4 \\\\ -t\lt 5 .\end{array} Dividing both sides by a negative number (and consequently reversing the inequality symbol), the inequality above is equivalent to \begin{array}{l}\require{cancel} -t\lt 5 \\\\ \dfrac{-t}{-1}\lt \dfrac{5}{-1} \\\\ t\gt -5 .\end{array} Hence, the solution set is \begin{array}{l}\require{cancel} \text{Set Builder Notation: } \{t|t\gt -5\} \\\text{Interval Notation: } (-5,\infty) .\end{array}