Browse · MATH
Printjmc
algebra senior
Problem
Let and be constants, and suppose that the inequality is true if and only if either or Given that find the value of
Solution
We first unpack the statement or The inequality is equivalent to which is in turn equivalent to Therefore, we have either or so the solution set for is The sign of the expression changes at and which means that and must be the numbers and in some order. Furthermore, since and are endpoints of a closed interval (that is, they are included in the solution set), it must be the case that and are and in some order, because the inequality is true when or but is not true when (since that would make the denominator zero). Since we have and and then
In conclusion, the given inequality must be To check that the solution to this inequality is we can build a sign table, where is the expression on the left-hand side: \begin{array}{c|ccc|c} &$x-24$ &$x-26$ &$x+4$ &$f(x)$ \\ \hline$x<-4$ &$-%%DISP_0%%amp;$-%%DISP_0%%amp;$-%%DISP_0%%amp;$-$\\ [.1cm]$-4<x<24$ &$-%%DISP_0%%amp;$-%%DISP_0%%amp;$+%%DISP_0%%amp;$+$\\ [.1cm]$24<x<26$ &$+%%DISP_0%%amp;$-%%DISP_0%%amp;$+%%DISP_0%%amp;$-$\\ [.1cm]$x>26$ &$+%%DISP_0%%amp;$+%%DISP_0%%amp;$+%%DISP_0%%amp;$+$\\ [.1cm]\end{array}This shows that when and since for we indeed have the solution set Thus,
In conclusion, the given inequality must be To check that the solution to this inequality is we can build a sign table, where is the expression on the left-hand side: \begin{array}{c|ccc|c} &$x-24$ &$x-26$ &$x+4$ &$f(x)$ \\ \hline$x<-4$ &$-%%DISP_0%%amp;$-%%DISP_0%%amp;$-%%DISP_0%%amp;$-$\\ [.1cm]$-4<x<24$ &$-%%DISP_0%%amp;$-%%DISP_0%%amp;$+%%DISP_0%%amp;$+$\\ [.1cm]$24<x<26$ &$+%%DISP_0%%amp;$-%%DISP_0%%amp;$+%%DISP_0%%amp;$-$\\ [.1cm]$x>26$ &$+%%DISP_0%%amp;$+%%DISP_0%%amp;$+%%DISP_0%%amp;$+$\\ [.1cm]\end{array}This shows that when and since for we indeed have the solution set Thus,
Final answer
64