Browse · MATH
Printjmc
algebra intermediate
Problem
Find all values of that satisfy
Solution
Combining the terms on the right-hand side, we have Then, moving all the terms to the left-hand side and combining denominators again, we get We try to factor the numerator. Using the rational root theorem to test for rational roots, we see that is a root of Then, doing the polynomial division gives so we have Since has a positive coefficient, and its discriminant is which is negative, it follows that for all Thus, the above inequality is equivalent to We make a sign table for : \begin{array}{c|ccc|c} &$x-3$ &$x+1$ &$x-1$ &$f(x)$ \\ \hline$x<-1$ &$-%%DISP_0%%amp;$-%%DISP_0%%amp;$-%%DISP_0%%amp;$-$\\ [.1cm]$-1<x<1$ &$-%%DISP_0%%amp;$+%%DISP_0%%amp;$-%%DISP_0%%amp;$+$\\ [.1cm]$1<x<3$ &$-%%DISP_0%%amp;$+%%DISP_0%%amp;$+%%DISP_0%%amp;$-$\\ [.1cm]$x>3$ &$+%%DISP_0%%amp;$+%%DISP_0%%amp;$+%%DISP_0%%amp;$+$\\ [.1cm]\end{array}We see that when or Since the inequality is nonstrict, we also include the values of such that that is, only Therefore, the solution to the inequality is
Final answer
(-1, 1) \cup [3, \infty)