If n is a positive integer, which of the following could be equal to ((n+1)^3)−((n^3)+1)?
A. 7^3(6^3−1)
B. 7^3(6^3+1)
C. 2∗26∗27
D. 3∗31∗32
E. 0
You can do this step-by-step by hand, but it will be a hell of a lot easier if you have the cubic expansion for a binomal handy:
(a+b)^3 = a^3 + 3(a^2)b + 3(a)b^2 + b^3
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