Quadratic Equations: Discriminant Analysis

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Questions and Answers

What is the nature of roots for the equation $x^2 - 3x - 10 = 0$?

  • No real roots
  • Two distinct real roots (correct)
  • Two complex roots
  • One real root

Which pair of numbers has a sum of 27 and a product of 182?

  • 11 and 16
  • 9 and 18
  • 7 and 20
  • 10 and 17 (correct)

How many articles were produced if the cost of production of each article is twice the number of articles and the total cost is ₹90?

  • 5 articles
  • 15 articles
  • 20 articles
  • 10 articles (correct)

What are the two consecutive positive integers whose sum of squares equals 365?

<p>14 and 15 (C)</p> Signup and view all the answers

If the altitude of a right triangle is 7 cm less than its base and the hypotenuse is 13 cm, which equation represents this situation?

<p>$base^2 + (base - 7)^2 = 13^2$ (C)</p> Signup and view all the answers

What is the value of the discriminant for the equation $3x^2 - 2x + \frac{1}{3} = 0$?

<p>0 (C)</p> Signup and view all the answers

How many distinct real roots does the equation $3x^2 - 2x + \frac{1}{3} = 0$ have?

<p>Two equal real roots (A)</p> Signup and view all the answers

What are the roots of the equation $3x^2 - 2x + \frac{1}{3} = 0$?

<p>$\frac{1}{3}$ and $\frac{1}{3}$ (A)</p> Signup and view all the answers

What values of $a$, $b$, and $c$ correspond to the quadratic equation $3x^2 - 2x + \frac{1}{3} = 0$?

<p>$a = 3$, $b = -2$, $c = \frac{1}{3}$ (A)</p> Signup and view all the answers

Why is the discriminant important in determining the nature of the roots of a quadratic equation?

<p>It indicates the number and nature of the roots. (D)</p> Signup and view all the answers

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Study Notes

Quadratic Equations and Discriminants

  • Standard form of a quadratic equation: ( ax^2 + bx + c = 0 ), where ( a, b, c ) are real numbers, and ( a \neq 0 ).
  • Discriminant formula: ( D = b^2 - 4ac ).
  • Nature of roots based on discriminant:
    • If ( D > 0 ): Two distinct real roots.
    • If ( D = 0 ): Two equal real roots.
    • If ( D < 0 ): No real roots; complex roots exist.

Example and Applications

  • For the equation ( 3x^2 - 2x + \frac{1}{3} = 0 ):
    • ( a = 3, b = -2, c = \frac{1}{3} ).
    • Discriminant ( D = (-2)^2 - 4 \cdot 3 \cdot \frac{1}{3} = 0 ), indicating two equal real roots.
    • Roots found: ( x = \frac{-b}{2a} = \frac{1}{3} ).

Factorization Method for Roots

  • Example quadratic ( 2x^2 - 3x + 1 = 0 ):
    • One root found by substitution: ( x = 1 ).
    • Factorization leads to ( (2x - 1)(x - 1) = 0 ) yielding roots ( x = \frac{1}{2}, 1 ).

Solving Specific Quadratic Equations

  • Roots of quadratic equations can be found through factorization:
    • Example equations to factor:
      • ( x^2 - 3x - 10 = 0 )
      • ( 2x^2 + x - 6 = 0 )
      • ( \sqrt{2}x^2 + 7x + 5\sqrt{2} = 0 )
      • ( 2x^2 - x + \frac{1}{8} = 0 )
      • ( 100x^2 - 20x + 1 = 0 )

Finding Roots Through the Quadratic Formula

  • Roots can also be calculated using the formula:
    • ( x = \frac{-b \pm \sqrt{D}}{2a} ) where ( D = b^2 - 4ac ).

Additional Problems

  • Find two numbers whose sum is 27 and product is 182.
  • Find consecutive positive integers such that the sum of their squares is 365.
  • Determine sides of a right triangle where one side is shorter than the hypotenuse by 7 cm and hypotenuse is 13 cm.
  • Solve for the number of items produced by a pottery industry given total production costs.

Key Takeaways

  • Quadratic equations may possess a maximum of two roots, related to their factorization and polynomial behavior.
  • Utilize the discriminant to assess the nature of roots quickly.
  • Factorization is a valuable method to derive roots when applicable.
  • The quadratic formula is a universal tool for finding roots.

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