Question x-2-12

2.2 Nonlinear Equations in One Variable - Quadratic solving (factoring, quadratic formula, completing square)
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x2-12x+27=0

How many distinct real solutions does the given equation have?

A.

Exactly two

B.

Exactly one

C.

Zero

D.

Infinitely many

x 2 - 12 x + 27 = 0 How many distinct real solutions does the

Hard-difficulty · SAT Math · Nonlinear Equations in One Variable — Quadratic solving (factoring, quadratic formula, completing square). Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice A is correct. The number of solutions of a quadratic equation of the form a x 2 + b x + c = 0 , where a , b , and c are constants, can be determined by the value of the discriminant, b2-4ac. If the value of the discriminant is positive, then the quadratic equation has exactly two distinct real solutions. If the value of the discriminant is equal to zero, then the quadratic equation has exactly one real solution. If the value of the discriminant is negative, then the quadratic equation has zero real solutions. In the given equation, x2-12x+27=0, a = 1 , b = - 12 , and c = 27 . Substituting these values for a , b , and c in b2-4ac yields -122-4127, or 36 . Since the value of its discriminant is positive, the given equation has exactly two distinct real solutions.

Choice B is incorrect and may result from conceptual or calculation errors.

Choice C is incorrect and may result from conceptual or calculation errors.

Choice D is incorrect and may result from conceptual or calculation errors.