Question f-x-x-
If the given function is graphed in the xy-plane, where , what is an x-intercept of the graph?
f x = x 2 - 18 x - 360 If the given function f is
Medium-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. It's given that . The x-intercepts of a graph in the xy-plane are the points where . Thus, for an x-intercept of the graph of function , . Substituting for in the equation yields . Factoring the right-hand side of this equation yields . By the zero product property, and . Subtracting from both sides of the equation yields . Adding to both sides of the equation yields . Therefore, the x-intercepts of the graph of are and . Of these two x-intercepts, only is given as a choice.
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.
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