Explanation
Correct answer: B.
Choice B is correct. It's given that , which can be rewritten as . Since the coefficient of the -term is positive, the graph of in the xy-plane opens upward and reaches its minimum value at its vertex. For an equation in the form , where , , and are constants, the x-coordinate of the vertex is . For the equation , , , and . It follows that the x-coordinate of the vertex is , or . Therefore, reaches its minimum when the value of is .
Desmos solution:
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect. This is one of the x-coordinates of the x-intercepts of the graph of in the xy-plane.
Choice C
Choice C is incorrect. This is one of the x-coordinates of the x-intercepts of the graph of in the xy-plane.
Choice D
Choice D is incorrect. This is the y-coordinate of the vertex of the graph of in the xy-plane.