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Use the parabola tool to graph the quadratic function f(x) =2x2 - 12x+11 graph the parabola by first plotting its vertex and then plotting a second point on the parabola.

User Eldblz
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1 Answer

3 votes

Answer:

  • vertex: (3, -7)
  • point: (4, -5)

Explanation:

You want the vertex and another point on the parabola f(x) = 2x² -12x +11.

Vertex

The equation can be put into vertex form as follows:

f(x) = 2(x² -6x) +11 . . . . . . . factor the leading coefficient from the variable terms

f(x) = 2(x² -6x +9) +11 -2(9) . . . . add (6/2)² = 9 inside parentheses, subtract the same amount outside

f(x) = 2(x -3)² -7 . . . . . . . . simplify to vertex form

Comparing this to the vertex form equation ...

f(x) = a(x -h)² +k

we see that a=2, h=3, k=-7.

The vertex is (h, k) = (3, -7). This is one point on the parabola.

A second point

We can use a value for x that is near the value of h to obtain another point on the parabola without much work. Using x = 4, we have ...

f(4) = 2(4 -3)² -7 = 2(1) -7 = -5

Another point is (x, y) = (4, -5).

You can plot the vertex (3, -7) and the point (4, -5) to obtain your graph of the parabola using the parabola tool.

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Additional comment

The points and the parabola are shown in the attached graph.

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Use the parabola tool to graph the quadratic function f(x) =2x2 - 12x+11 graph the-example-1
User Jon Colverson
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8.4k points

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