Kubikroden af et tal, er det tal, som ganget med sig selv 3 gange, giver tallet.
Det skrives med symbolet:
![sqrt[3]{a}](data:image/png;base64,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)
(Hvor a er tallet.)
For eksempel, hvis vi skal finde kubikroden af 125:
![sqrt[3]{125}=5](data:image/png;base64,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)
da

Kubikrod giver kun én rod, og man kan godt tage kubikroden af et tal, der er mindre end 0.
Eksempel:
Vi finder kubikroden af -64:
![sqrt[3]{-64}=-4](data:image/png;base64,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)
da

Man kan også skrive kubikroden som en potens:
Det skrives med symbolet:
(Hvor a er tallet.)
For eksempel, hvis vi skal finde kubikroden af 125:
da
Kubikrod giver kun én rod, og man kan godt tage kubikroden af et tal, der er mindre end 0.
Eksempel:
Vi finder kubikroden af -64:
da
Man kan også skrive kubikroden som en potens: