In the xy-plane the graph of the function q has a parabola. The graph intersects the x-axis at (-1,0), and (r, 0). If the vertex of q occurs at the point (2,4), what is the value of r?
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Answer:
r = 5
Step-by-step explanation:
The graph intersects the x-axis at (-1,0), and (r, 0). If the vertex of q occurs at the point (2,4), what is the value of r?
Note that if the vertex is given, then we also have the equation of the axis of symmetry: it is x = 2. Now, the first x-intercept, (-1,0), is 3 units to the left of this axis of symmetry; therefore, the second intercept must be 3 units to the right of this axis, at x = 2+3, or x = 5. Therefore, r = 5.