MathDB
Adding Functions

Source: 1968 AHSME Problem #5

August 31, 2011
functionAMC

Problem Statement

If f(n)=13n(n1)(n+2)f(n)=\tfrac{1}{3}n(n1)(n+2), then f(r)−f(r−1)f(r)-f(r-1) equals:
<spanclass=′latex−bold′>(A)</span> r(r+1)<spanclass=′latex−bold′>(B)</span> (r+1)(r+2)<spanclass=′latex−bold′>(C)</span> 13r(r+1)<spanclass=′latex−bold′>(D)</span> 13(r+1)(r+2)<spanclass=′latex−bold′>(E)</span> 13r(r+1)(r+2)<span class='latex-bold'>(A)</span>\ r(r+1) \qquad <span class='latex-bold'>(B)</span>\ (r+1)(r+2) \qquad <span class='latex-bold'>(C)</span>\ \tfrac{1}{3}r(r+1) \qquad\\ <span class='latex-bold'>(D)</span>\ \tfrac{1}{3}(r+1)(r+2) \qquad <span class='latex-bold'>(E)</span>\ \tfrac{1}{3}r(r+1)(r+2)
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