Math Help - critical numbers...

1. critical numbers...

I just want to double check this. If I am given a function (such as x+(1/x)) where 0 is not in its domain, but comes up as a zero when I'm finding critical numbers, it's not a critical number because it's undefined and not in the domain anyway?

Thanks.

2. Originally Posted by Esiuol
I just want to double check this. If I am given a function (such as x+(1/x)) where 0 is not in its domain, but comes up as a zero when I'm finding critical numbers, it's not a critical number because it's undefined and not in the domain anyway?

Thanks.
If by a critical number you mean a zero of the derivative 0 is not a zero of
the derivative of x+1/x, as the derivative is 1-1/(x^2) which is also
undefined at x=0.

RonL