Lesson 9-2Graphing y = ax + bx + c

Objective: To graph equations of the form f(x) = ax + bx + c and interpret these graphs.

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In Lesson 9-1 we investigated graphs of y = ax2 and y = x2

y = a(0) + b(0) + c2

y = ax + bx + c2

y = 0 + 0 + c

y = c Therefore c in a quadratic equation is the y-intercept of the parabola

Name the y-intercept for each function.

Example 1

a. Given the equation y = -x - 4, tell whether the parabola opens up or down.

b. Identify the y-intercept without graphing it.

c. Make a table of values and graph the function.

d. Identify its axis of symmetry and vertex.

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Example 2

Consider the equation f(x) = 2x - 8x + 6 and use a table of values to answer the questions. Your table should include negative and positive values.

• Identify the vertex of the parabola by using your table of values if possible?

• What is the equation for the axis of symmetry of the parabola?

• Find the y-intercept without graphing.

• Graph the parabola.

• What are the x-coordinates of the two points where y = 16?

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Example 2

Consider the equation f(x) = 2x - 8x + 6 and use a table of values to answer the questions. Your table should include negative and positive values.

• Identify the vertex of the parabola by using your table of values if possible?

• What is the equation for the axis of symmetry of the parabola?

• Find the y-intercept without graphing.

• Graph the parabola.

• What are the x-coordinates of the two points where y = 16?

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Read Lesson 9-3 and fill in study guide. In Lesson 9-2 complete #5-9, 12-13, 15-18.

Homework ~ Friday March 26

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