A student states: “For any polynomial of degree

MATHEMATICS · Multi-part · AP · Calculus AB · Differentiation: Composite, Implicit, and Inverse Functions · Differentiation: Composite, Implicit, and Inverse Functions

Problem

A student states: “For any polynomial R(x)R(x) of degree dd, the nnth derivative R(n)(x)R^{(n)}(x) is zero whenever n>dn>d, and when n≤dn\le d the coefficient of the highest-degree term in R(n)(x)R^{(n)}(x) always contains a factorial factor.” Evaluate this statement. (a) Using derivative properties, explain rigorously why R(n)(x)R^{(n)}(x) is identically zero for all n>dn>d. (b) For n≤dn\le d, describe how repeated differentiation affects the coefficient of the leading term of R(x)R(x), and clarify the role of factorial factors in your explanation. (c) Let S(x)=7x3−2x+5S(x)=7x^{3}-2x+5. Compute S′(x)S'(x), S′′(x)S''(x), and S(3)(x)S^{(3)}(x). Discuss how your results support or contradict the student’s claim.

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