We are looking for a function whose derivative is x³. From the power rule for derivatives, it ought to be a function involving a higher power of x. This gives us three choices: B, D or E.

To check choice B, take the derivative of x⁴/4 + C. You get 4x³/4, and the 4's cancel to leave x³. So, choice B is the correct choice. (Choice D uses the "dx" wrongly; it belongs with the integral sign -- s)ee the definition box above. Choice E has the wrong derivative: 4x³/3.

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