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  <question type="description">
    <name>
      <text>2.5.1.8 Charateristics and properties of straight lines: exercises with solution</text>
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      <text><![CDATA[<hr>
<h4 class="HELM_example">Exercises</h4>
<ol><li>State the general form of the equation of a straight line explaining the role of each of the terms in your answer.</li>
<li>State which of the following functions will are straight lines: <br></li>
<br>
<ol class="HELM_parts_inline">
<li>\(f(x)=3x-3\),</li>
<li>\(f(x)=(x)^(1/2)\),</li>
<li>\(f(x)=1/x\),</li>
<li>\(f(x)=13\),</li>
<li>\(f(x)=-2-x\).</li>
</ol>
<br><br>
<li>Identify the gradient and the vertical intercept of the following ines: <br></li>
<br>
<ol class="HELM_parts_inline">
<li>\(f(x)=2x+1\),</li>
<li>\(f(x)=3)\),</li>
<li>\(f(x)=-2x\),</li>
<li>\(f(x)=-7-17x\),</li>
<li>\(f(x)=mx+c\).</li>
</ol>
</ol>
<br>
<br>
<h4 class="HELM_solution">Solution</h4>
<ol>
<li>The general expression of a straight line is \(y=ax+b\), where \(x\) is is the independent variable, \(y\) is the dependent variable, \(a\) is the gradient and \(b\) is the vertical intercept. <br></li>
<li>Equations (a), (d) and (e) are examples of straight lines.<br></li>

<li>Let introduce the pair (gradient, vertical intercept). Then, the solution is given by
<br> <br>
<ol class="HELM_parts_inline">
<li>\((2, 1)\),</li>
<li>\((0, 3)\),</li>
<li>\((-2, 0)\),</li>
<li>\((-7, -17)\),</li>
<li>\((c, m)\).</li>
</ol>
<br></li>
</ol>]]></text>
    </questiontext>
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