What are the solutions of the quadratic equation (x – 8)2 – 13(x – 8) + 30 = 0? Use u substitution to solve.

Let u = x − 8. The equation becomes u² − 13u + 30 = 0, which factors as (u − 10)(u − 3) = 0, so u = 10 or u = 3. Substituting back gives x − 8 = 10 or x − 8 = 3, so x = 18 or x = 11. The correct choice is D, x = 11 and x = 18.

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