A cubic function f is defined for x ∈ R as f (x) = x^{3}+ (1 - k^{2})x + k, where k is a constant. Show that -k is a root of f.

How would I go about doing this? Help appreciated! :)

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- Mar 9th 2013, 10:00 AMHelenMc9Cubic Functions
A cubic function f is defined for x ∈ R as f (x) = x

^{3}+ (1 - k^{2})x + k, where k is a constant. Show that -k is a root of f.

How would I go about doing this? Help appreciated! :) - Mar 9th 2013, 10:17 AMPlatoRe: Cubic Functions
- Mar 9th 2013, 10:24 AMHelenMc9Re: Cubic Functions
Aah yes it's equal to zero because -k is a root... I know what to do now! :) thanks!!

- Mar 9th 2013, 11:17 AMHallsofIvyRe: Cubic Functions
By the way, "root" is the wrong word here. You can find a "root" of an

**equation**such as f(x)= 0, or a "zero" of a function, that being, of course, the root of the equation f(x)= 0. - Mar 9th 2013, 11:42 AMPlatoRe: Cubic Functions
There does seem to be general agreement on that.

See zero here and root there.