Now consider {{MATH_72}}. This function is undefined at the roots of {{MATH_73}} Hence it is undefined at {{MATH_74}} and {{MATH_75}}. It looks like both curves {{MATH_76}} and {{MATH_77}} would work. Distinguishing between these two curves is easy enough if we evaluate at {{MATH_78}}. Check it out. {{ENV_79}} Since this is negative, we see that {{MATH_80}} corresponds to curve {{MATH_81}}.