What happens if you are trying a first and second derivative test on a function and they do not exist on the function (they only give errors)(adsbygoogle = window.adsbygoogle || []).push({});

Also, is it possible that the critical values of a function (max, mins, points of inflection) don't extist on a function

example

y=-4x(x^2 -6)^0.5

y'=-8(x^2 -6)^-0.5 (x^2 -3)

y''=8x(x^2-6)^-1.5 (x^2 -9)

When finding the max and mins set y'=0

and i find that the max and mins are at -root3 and root3 (i can't type a square root sign)

but they don't exist in the function ( when i susbstitute that into the function i get error because you can't squaer root a negative number.

What do i do?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Derivatives that don't exist

**Physics Forums | Science Articles, Homework Help, Discussion**