What is 64x6 + 27 written as a sum of cubes?

Rewrite each term as a cube: 64x^6 = (4x^2)^3 because 4^3 = 64 and (x^2)^3 = x^6. Also, 27 = 3^3. So the expression is (4x^2)^3 + 3^3, which is choice B.

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