Understanding Quadratic Equations through Graphing: Solutions and Zeros Explained
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In this lesson, we review how to solve quadratic equations by graphing. We explore the concept of zeros—where the graph intersects the x-axis—and discuss how many solutions a quadratic can have. Quadratics can have two, one, or no solutions based on their graph behavior. We'll examine various graphs, identify the solutions (x-intercepts), and learn how to write the corresponding equations from these graphs. Use tables to find solutions and understand the relationships between graphing and quadratic equations more deeply.
Understanding Quadratic Equations through Graphing: Solutions and Zeros Explained
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Presentation Transcript
Solving Quadratic Equations By Graphing
Vocab review Do you remember from unit 1? Zeros – the place where the graph crosses the x-axis A.K.A – x-intercepts or Roots or solutions Zeros
How many solutions does a Quadratic have? Sometimes is may have less than 2 solutions. Let’s see what that looks like. Two solutions because the highest exponent is 2
How many solutions does a Quadratic have? 2 solutions The graph crosses the x-axis twice 1 solution The graph crosses the x-axis once No solution The graph never crosses the x-axis
How many solutions does a Quadratic have? 2 solutions The graph crosses the x-axis twice 1 solution The graph crosses the x-axis once No solution The graph never crosses the x-axis
Your turn! • How many solutions do each of these graphs have? 1. 2. 3. 1 solution 2 solutions 2 solutions
Identifying the solutions from the graph X = -2, 2 X = -3 X = -4, 1
You try! • Identify the solutions from the graph X = -2, 2 No solution X = 0
Writing the equation from the graph. • Using the solutions from 2 slides ago X = -2, 2 X = -3 X = -4, 1 Y = (x + 3)2 Y = -(x + 4)(x – 1) Y = (x – 2)(x + 2)
You try! Write the equation of each graph. 1. 2. 3. Y = (x + 5)(x – 3) Y = (x + 4)(x – 1) Y = - (x – 4)2
Finding the solutions from a table Ex: 1 This table is of a Quadratic with 2 two solutions Remember: The solution is also called a zero or x-intercept. Meaning that the y-coordinate of the solution is 0 These are my solutions X = 5, 3
Finding the sol’n from a table cont. Ex: 2 Find the solutions. X = -1 and 1
Finding the sol’n from a table cont. Ex: 3 Find the solutions. This problem only has one solution X = 2 Ex: 4 This problem no solution
Finding the sol’n from a table cont. Ex: 5 Find the solutions. This problem has two solution but only one is listed on the table X = 0 , 4
Finding the solutions from a graph There are zeros between -5 and -4 and between 1 and 2
Solutions from a table cont. Ex: 6 Find the interval where the zero is. The zeros are between 2 and 3 and between 5 and 6