What is the product? the fraction with numerator 3 k and denominator k plus 1 times the fraction with numerator k squared minus 1 and denominator 3 k cubed

Factor the difference of squares: k² − 1 = (k − 1)(k + 1). Then (3k/(k + 1))((k − 1)(k + 1)/(3k³)) simplifies by canceling 3 and (k + 1), and reducing k/k³ to 1/k². The product is (k − 1)/k², choice C.

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