The x becomes negative because the negative sign at the start of the parenthesis distributes to everything inside parenthesis so x becomes -x and the double negative becomes +6 so that is why
Answer:
C - He substituted incorrectly when calculating the constant of variation.
Hey!
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Solution:

Cube the coefficients.

Multiply the exponents.

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Answer:
Option D.
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Hope This Helped! Good Luck!