Site logo
    Add a listing
    Add a listing

    NCERT| RBSE, CBSE | CLASS TENTH, SUBJECT MATHS, UNIT SECOND, Quadratic Equations, Solution of a Quadratic Equation by Factorisation, Nature of Roots.

    Delving Deeper into Quadratic Equations:

    1. Quadratic Equations:

    We already covered the basics of a quadratic equation in the form ax^2 + bx + c = 0, where x is the unknown variable and a, b, and c are constants (a ≠ 0). Let’s explore some key points:

    • Standard Form: This is the most common form where all terms are arranged with x exponents in decreasing order.
    • Degree: The highest exponent of x determines the degree, hence quadratic = degree 2.
    • Roots/Solutions: These are the values of x that make the equation true, found using various methods.

    2. Solution by Factorisation:

    This method involves rewriting the quadratic equation as a product of two linear expressions (binomials). Imagine factoring a polynomial like breaking a bigger shape into smaller, simpler ones. Here’s how it works:

    • Steps:
      1. Find two numbers that multiply to give c and add up to b.
      2. Group the terms and factor out these numbers from each group.
      3. Use the zero product property: if xy = 0, then either x = 0 or y = 0.
      4. Solve for x by setting each factor equal to zero and obtaining the roots.
    • Example: Solve x^2 + 5x – 6 = 0.
      1. Find 2 and 3 (2 * 3 = 6 and 2 + 3 = 5).
      2. Group and factor: (x^2 + 2x) + (3x – 6) = x(x + 2) + 3(x – 2).
      3. Apply zero product property: x(x + 2) = 0 or 3(x – 2) = 0.
      4. Solve: x = 0, -2.

    3. Nature of Roots:

    The discriminant, b^2 – 4ac, plays a crucial role in determining the type and number of roots:

    • Positive Discriminant (b^2 – 4ac > 0): Two distinct real roots. Think of the seesaw balancing at two different points.
    • Zero Discriminant (b^2 – 4ac = 0): One real root (double root). The seesaw balances at a single point where both sides touch.
    • Negative Discriminant (b^2 – 4ac < 0): Two complex roots. The seesaw cannot balance on the real number line and needs to venture into the complex plane.

    By calculating the discriminant, you can predict the nature of the roots before even solving the equation.

    10 Questions and Answers on Quadratic Equations:

    1. What is a quadratic equation?

    A quadratic equation is an equation of the form ax^2 + bx + c = 0, where x is the unknown variable, a, b, and c are constants (a ≠ 0), and the highest exponent of x is 2.

    2. How can we solve a quadratic equation?

    There are three main methods:

    • Factorization: Rewriting the equation as a product of two linear expressions.
    • Completing the square: Manipulating the equation to form a perfect square trinomial.
    • Quadratic formula: A general formula applicable to any quadratic equation, regardless of complexity.

    3. What is the quadratic formula?

    The quadratic formula is: x = (-b ± √(b^2 – 4ac)) / 2a, where a, b, and c are the coefficients from the standard form equation. It gives both roots, even if they are complex.

    4. What is the discriminant?

    The discriminant, b^2 – 4ac, helps determine the nature of the roots:

    • Positive discriminant: Two distinct real roots.
    • Zero discriminant: One real root (double root).
    • Negative discriminant: Two complex roots.

    5. What are the different types of roots?

    • Real roots: Solutions that exist on the real number line.
    • Double root: When the two roots are the same value.
    • Complex roots: Solutions that involve the imaginary unit “i” and exist in the complex plane.

    6. Can you explain factorization in more detail?

    Factorization involves finding two numbers that multiply to c and add up to b. You then group the terms and factor these numbers from each group. Finally, you use the zero product property to solve for x.

    7. How can we use the discriminant without solving the equation?

    By simply calculating the discriminant, you can predict the nature of the roots before even solving the equation. This can be helpful in determining the appropriate solution method.

    8. Are there any real-world applications of quadratic equations?

    Absolutely! Examples include calculating projectile motion, modeling loan payments, finding the resonant frequencies of waves, and studying planetary orbits.

    9. Where can I learn more about quadratic equations?

    There are many online resources and textbooks available. Some popular options include Khan Academy, Math is Fun, Purplemath, and your local library.