NCERT Exemplar Solutions
Class 10 - Mathematics - CHAPTER 4: Quadatric Equation - Exercise 4.2
Question 4

Question. 4

Does there exist a quadratic equation with rational coefficients but irrational roots? Justify.

Answer:

Yes.

Detailed Answer with Explanation:

Let us check step by step:

  1. A quadratic equation is of the form \(ax^2 + bx + c = 0\), where \(a, b, c\) are numbers called coefficients.
  2. Rational coefficients means \(a, b, c\) are either integers or fractions (numbers that can be written as \(\dfrac{p}{q}\)).
  3. Irrational roots means the solutions (values of \(x\)) cannot be written as a simple fraction, like \(\sqrt{2}, \sqrt{3}, \pi\), etc.
  4. Consider the equation: \(x^2 - 2 = 0\).
  5. Here, the coefficients are:
    • \(a = 1\)
    • \(b = 0\)
    • \(c = -2\)
    All of these are rational numbers.
  6. Now solve: \(x^2 - 2 = 0 \implies x^2 = 2\).
  7. Taking square root: \(x = \pm \sqrt{2}\).
  8. But \(\sqrt{2}\) is an irrational number.

So this quadratic equation has rational coefficients but irrational roots. Hence, the answer is Yes.

NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 4: Quadatric Equation – Exercise 4.2 | Detailed Answers