x^2 - 2x - 3 = 0. - United Radiology

April 22, 2026 · United Radiology

["# Solving the Quadratic Equation: x² - 2x - 3 = 0", "When solving quadratic equations, few problems are both fundamental and ubiquitous as those involving the general form:", "[
\nax^2 + bx + c = 0
\n]", "One of the classic and easily solvable examples is:", "[
\nx^2 - 2x - 3 = 0
\n]", "This article will walk you through solving this quadratic equation step-by-step, exploring its roots, interpreting the results, and understanding its broader mathematical significance. Whether you're a student, teacher, or self-learner, mastering this equation helps build a solid foundation in algebra.", "---", "## Understanding the Equation", "The given equation is:", "[
\nx^2 - 2x - 3 = 0
\n]", "This is a standard quadratic equation where:
\n- ( a = 1 )
\n- ( b = -2 )
\n- ( c = -3 )", "Since ( a <br/>\neq 0 ), the equation is quadratic and fits the general form ( ax^2 + bx + c = 0 ), allowing us to apply well-known solution methods such as factoring, completing the square, or using the quadratic formula.", "---", "## 1. Factoring the Quadratic Expression", "Factoring is often the quickest approach when the quadratic expression is factorable. We aim to express ( x^2 - 2x - 3 ) as a product of two binomials:", "[
\nx^2 - 2x - 3 = (x + m)(x + n)
\n]", "We need two numbers ( m ) and ( n ) such that:
\n- ( m \cdot n = -3 ) (the constant term)
\n- ( m + n = -2 ) (the coefficient of the linear term)", "By testing integer pairs that multiply to -3, we find ( m = 1 ) and ( n = -3 ) satisfy both conditions:", "[
\n(x + 1)(x - 3) = 0
\n]", "Verification: Multiplying back:
\n[
\n(x + 1)(x - 3) = x^2 - 3x + x - 3 = x^2 - 2x - 3 \quad \ ext{(Correct)}
\n]", "---", "## 2. Applying the Zero Product Property", "Setting each factor to zero:", "[
\nx + 1 = 0 \quad \Rightarrow \quad x = -1
\n]
\n[
\nx - 3 = 0 \quad \Rightarrow \quad x = 3
\n]", "Thus, the solutions to ( x^2 - 2x - 3 = 0 ) are:", "[
\nx = -1 \quad \ ext{and} \quad x = 3
\n]", "These are the roots or zeros of the quadratic function.", "---", "## Why Factoring Works Here", "Factoring succeeds for this quadratic because its constant term and linear coefficient are small integers, making it easy to identify the right pair. For more complex quadratics with irrational, complex, or large integer coefficients, methods like the quadratic formula or completing the square become necessary.", "---", "## 3. Using the Quadratic Formula", "For any equation ( ax^2 + bx + c = 0 ), the solutions are given by:", "[
\nx = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
\n]", "Plugging in ( a = 1 ), ( b = -2 ), ( c = -3 ):", "[
\nx = \frac{-(-2) \pm \sqrt{(-2)^2 - 4(1)(-3)}}{2(1)} = \frac{2 \pm \sqrt{4 + 12}}{2} = \frac{2 \pm \sqrt{16}}{2}
\n]", "[
\nx = \frac{2 \pm 4}{2}
\n]", "Now compute both possibilities:", "[
\nx = \frac{2 + 4}{2} = \frac{6}{2} = 3
\n]
\n[
\nx = \frac{2 - 4}{2} = \frac{-2}{2} = -1
\n]", "Again, we confirm the roots: ( x = -1 ) and ( x = 3 ).", "---", "## 4. Graphical Interpretation", "The equation ( x^2 - 2x - 3 = 0 ) represents a parabola opening upwards (since the coefficient of ( x^2 ) is positive). The roots correspond to the points where the parabola crosses the x-axis.", "Factoring shows the parabola intersects the x-axis at ( x = -1 ) and ( x = 3 ), confirming our algebraic solutions.", "---", "## 5. Applications of the Roots", "Solving quadratic equations like ( x^2 - 2x - 3 = 0 ) forms the basis for understanding:", "- Physics: Projectile motion and quadratic trajectories
\n- Economics: Profit maximization and break-even analysis
\n- Engineering: Design and optimization problems
\n- Computer Science: Algorithmic modeling and computational geometry", "Understanding the roots helps determine critical points such as maximum/minimum values, intersection points, and feasibility in real-world models.", "---", "## Summary", "The quadratic equation ( x^2 - 2x - 3 = 0 ) serves as a classic example of algebraic problem-solving. It can be solved efficiently by factoring into:", "[
\n(x + 1)(x - 3) = 0
\n]", "yielding the real roots:", "[
\nx = -1 \quad \ ext{and} \quad x = 3
\n]", "This equation illustrates fundamental algebraic principles and acts as a gateway to more complex quadratic analysis. Whether you're solving equations symbolically or graphically, mastering such quadratics builds confidence in algebraic reasoning and expands your analytical toolkit.", "---", "## Further Learning Resources", "- Algebra Fundamentals: Factoring Techniques
\n- Quadratic Formula and Discriminant Explained
\n- Graphing Parabolas: Roots and Vertex", "Start mastering quadratics today—solving ( x^2 - 2x - 3 = 0 ) is just the beginning!"]

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