Math Problem Statement

Find the zeros by graphing: y = x^2 - 2x - 3

Solution

The problem asks us to find the zeros of the quadratic function y=x22x3y = x^2 - 2x - 3 by graphing. Here's how to solve it step-by-step:


Step 1: Understand Zeros of a Quadratic Function

The zeros (or roots) of a function are the xx-values where the graph intersects the xx-axis, meaning y=0y = 0. For y=x22x3y = x^2 - 2x - 3, we are looking for the values of xx that make the equation x22x3=0x^2 - 2x - 3 = 0.


Step 2: Identify the Zeros from the Graph

From the graph provided:

  • The parabola crosses the xx-axis at x=1x = -1 and x=3x = 3.

Thus, the zeros of y=x22x3y = x^2 - 2x - 3 are: x=1andx=3x = -1 \quad \text{and} \quad x = 3


Step 3: Verify the Results Algebraically (Optional)

The quadratic equation x22x3=0x^2 - 2x - 3 = 0 can be factored: x22x3=(x3)(x+1)=0x^2 - 2x - 3 = (x - 3)(x + 1) = 0 Setting each factor equal to zero: x3=0x=3x - 3 = 0 \quad \Rightarrow \quad x = 3 x+1=0x=1x + 1 = 0 \quad \Rightarrow \quad x = -1 This confirms the zeros are x=1x = -1 and x=3x = 3.


Final Answer:

The zeros of the quadratic function y=x22x3y = x^2 - 2x - 3 are: x=1andx=3x = -1 \quad \text{and} \quad x = 3

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Relative Questions:

  1. What are the steps to solve any quadratic equation by factoring?
  2. How do you determine the vertex of a parabola from its equation?
  3. Can all quadratic equations be factored? If not, what are the alternatives?
  4. How does the discriminant of a quadratic equation relate to the graph?
  5. What is the general shape of a parabola when the leading coefficient is positive?

Tip:

When solving quadratic equations graphically, always verify your results by substituting the zeros back into the equation to ensure y=0y = 0.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
Zeros of a Function

Formulas

Standard form of a quadratic equation: y = ax^2 + bx + c
Factoring method: (x - p)(x - q) = 0

Theorems

Zero Product Property

Suitable Grade Level

Grades 8-10