Notice that <em>f(x)</em> is only defined over the intervals 0 ≤ <em>x</em> < 3 and 3 < <em>x</em> ≤ 6; that is, all real numbers <em>x</em> between 0 and 3, and between 3 and 6, but <u>not including 3</u>. Since there is no definition for <em>f(x)</em> at <em>x</em> = 3, the value of <em>f</em> (3) is undefined.
