Quadratic From Graph

Name the Axis of Symmetry

• x = 1

• x = 0

Write a quadratic equation given the x intercepts and one other point.

Step 1: Write the factors.

The intercepts of this function are (6, 0) and (8, 0). Write the factors.

• (x-6) and (x-8)

• (x+6) and (x+8)

• (x-6) and (x+8)

• (x+6) and (x-8)

Tags

CCSS.HSF-IF.C.7A

Write a quadratic equation given the x intercepts and one other point.

Step 3: Write the equation in factored form.

Now, you know that the factors are (x-6) and (x-8) and a = -1. Write the equation of the graph in factored form.

• -(x-6)(x-8)

• -(x+6)(x+8)

• (x-6)(x+8)

• (x+6)(x-8)

Write a quadratic equation given the x intercepts and one other point.

Step 2: Find a.

Now that you know that the factors are (x-6) and (x-8), you must find a. Plug the coordinates of the vertex (7, 1) in for x and y and solve for a.

y = a(x-6)(x-8)

What is the value of a?

• a = 1

• a = -1

• a = 7

• a = -7

Write a quadratic equation given the x intercepts and one other point. Put the steps together. Find the factors. Solve for a by substituting in the extra point. Write the equation in factored form. The roots of the function are (-3, 0) and (5, 0). The point (4, -3) is also on the graph.

• y=4(x+3)(x-5)

• y=3/7(x-3)(x+5)

• y=-3(x-3)(x+5)

• y=3/7(x+3)(x-5)

Review: What are the vertex and axis of symmetry for the given graph?

• Vertex (1, -4) Axis of Symmetry: x=1

• Vertex (1, -4) Axis of Symmetry x = -4

• Vertex (-4, 1) Axis of Symmetry x=-4

• Vertex (-4, 1) Axis of Symmetry x = 1

Write a quadratic equation in vertex form given the vertex and another point.

1. Substitute the coordinates of the vertex (1, -4) in for h and k.

Vertex form: y=a(x-h)²+k

• (x+1)²-4=y

• (x-1)²-4=y

• (x + 1)(x - 3)=y

• x2 +2x - 3=y

What is the equation of the quadratic in the graph?

• y = (x+1)(x-2)

• y = (x-1)(x+2)

• y = (x+.5)² - 2.25

• y = (x-.5)(x-2)

Tags

CCSS.HSF-IF.C.7A

What is the equation of the quadratic function in the graph?

• y = x² - 2x - 8

• y = x² + 2x + 8

• y = x² - 2x + 8

• y = x² + 2x - 8

What is the equation of the quadratic function in the graph?

• y = (x + 1)² - 4

• y = (x - 1)² + 4

• y = (x - 1)² - 4

• y = (x + 1)² + 4