Which quadratic equation is equivalent to (x – 4)2 – (x – 4) – 6 = 0?
a. (u-4)^2-(u-4) - 6 = 0 where u = (x – 4)
b. u^2-(u- 4) – 6 = 0 where u = (x – 4)
c. 6u^2 – 16 –u -6 = 0 where u = (x – 4)
d. u^2-u-6 = 0 where u = (x – 4)

The answer is:

D.

We need to find an equivalent expression which replaces the factor "x-4" with the variable "u". To solve the problem, we just need to see which of the given expressions will be equal to the given expression even if the original expression "x-4" is changed to "u".

The original expression is:

So, rewriting "x-4" as "u", we have:

We can see that the obtained expression matches with the option D.

Hence, the correct option is:

D.

Have a nice day!