Start by computing {{MATH_507}} Now we need to find on what intervals is {{MATH_508}} positive and what intervals it is negative. To do this, solve {{MATH_509}} Factor {{MATH_510}} {{ENV_511}} So the critical points (when {{MATH_512}}) are when {{MATH_513}}, {{MATH_514}}, and {{MATH_515}}. Since the derivative, {{MATH_516}}, is a polynomial, it does not change the sign on intervals between its zeros, i.e., between the critical points. Now we can check the sign of {{MATH_517}} at some points {{CMD_518}}between{{CMD_519}} the critical points to find where {{MATH_520}} is positive and where negative: {{ENV_521}} From this we can make a sign table: