OG详解-OG1 数学2 Q12

Choice A is correct. It’s given that  p(n)= 7n³. Substituting 56  for p(n) in this   equation yields 56 = 7n³. Dividing each side of this equation by 7 yields  8 = n³. Taking the cube root of each side of this equation yields  2 = n. Therefore, when p (n) is equal to 56, the value of n is 2.
Choice B is incorrect and may result from conceptual or calculation errors.
Choice C is incorrect and may result from conceptual or calculation errors.
Choice D is incorrect and may result from conceptual or calculation errors.