Math Problem Statement

Plot five points on the parabola: y = x^2 - 2x - 1. The points include the vertex, two points to the left, and two points to the right.

Solution

To solve this problem, we need to:

  1. Identify the vertex of the parabola.
  2. Plot two points on either side of the vertex.

Step 1: Equation of the Parabola

The given equation is: y=x22x1y = x^2 - 2x - 1 This is a quadratic equation, and the graph of this equation is a parabola.

Step 2: Vertex of the Parabola

To find the vertex, we use the vertex formula for a quadratic equation y=ax2+bx+cy = ax^2 + bx + c, where:

  • a=1a = 1,
  • b=2b = -2,
  • c=1c = -1.

The x-coordinate of the vertex is given by: x=b2a=22(1)=1x = -\frac{b}{2a} = -\frac{-2}{2(1)} = 1

Now substitute x=1x = 1 into the equation to find the y-coordinate: y=(1)22(1)1=121=2y = (1)^2 - 2(1) - 1 = 1 - 2 - 1 = -2 So, the vertex is at (1,2)(1, -2).

Step 3: Choosing Points on Either Side

We will now choose two points to the left of x=1x = 1 (for example x=0x = 0 and x=1x = -1) and two points to the right (for example x=2x = 2 and x=3x = 3).

For x=0x = 0:

y=(0)22(0)1=1y = (0)^2 - 2(0) - 1 = -1 Point: (0,1)(0, -1)

For x=1x = -1:

y=(1)22(1)1=1+21=2y = (-1)^2 - 2(-1) - 1 = 1 + 2 - 1 = 2 Point: (1,2)(-1, 2)

For x=2x = 2:

y=(2)22(2)1=441=1y = (2)^2 - 2(2) - 1 = 4 - 4 - 1 = -1 Point: (2,1)(2, -1)

For x=3x = 3:

y=(3)22(3)1=961=2y = (3)^2 - 2(3) - 1 = 9 - 6 - 1 = 2 Point: (3,2)(3, 2)

Step 4: Plotting the Points

You can now plot the five points:

  1. (1,2)(1, -2) (the vertex),
  2. (0,1)(0, -1),
  3. (1,2)(-1, 2),
  4. (2,1)(2, -1),
  5. (3,2)(3, 2).

Would you like me to provide more details on graphing this or discuss any part of the solution?

Here are 5 related questions:

  1. What is the axis of symmetry for this parabola?
  2. How do you determine if a parabola opens upward or downward?
  3. What is the role of the coefficient aa in a quadratic equation?
  4. Can you determine the y-intercept directly from the equation?
  5. How would the graph change if b=0b = 0 in the equation?

Tip: The vertex is always the minimum or maximum point on the parabola, depending on whether it opens upward or downward.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Graphing Parabolas

Formulas

Quadratic equation y = ax^2 + bx + c
Vertex formula: x = -b / 2a

Theorems

Vertex Theorem of Parabolas
Symmetry of Parabolas

Suitable Grade Level

Grades 8-10