Which statement best describes the equation open paren x plus 5 close paren squared plus 4 times open paren x plus 5 close paren plus 12 is equal to 0 ?

Let u = x + 5. Then the equation becomes u² + 4u + 12 = 0, which is a quadratic equation in u. It is therefore quadratic in form, even though it has no real solutions; the discriminant is 4² − 4(1)(12) = −32. The correct choice is A: it can be rewritten as a quadratic using the substitution u = x + 5.

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