1. Introduction – परिचय
An equation of the form
ax2 + bx + c = 0, where a, b, c are real numbers and a ≠ 0,
is called a Quadratic Equation. The highest power of the variable is 2.
Quadratic equations are used in problems related to area, speed, time,
profit & loss and geometry.
जिस समीकरण में चर की अधिकतम घात 2 होती है, उसे द्विघात समीकरण कहते हैं।
इसका सामान्य रूप है:
ax2 + bx + c = 0, (a ≠ 0)
2. Quadratic Equation – द्विघात समीकरण
English: A quadratic equation is a polynomial equation of degree 2.
Examples:
- x2 − 5x + 6 = 0
- 2x2 + 7x − 4 = 0
हिंदी: द्विघात समीकरण वह बहुपद समीकरण है जिसकी घात 2 होती है।
3. Standard Form of a Quadratic Equation – द्विघात समीकरण का मानक रूप
English: The standard form of a quadratic equation is:
ax2 + bx + c = 0
- a = coefficient of x2
- b = coefficient of x
- c = constant term
हिंदी: द्विघात समीकरण का मानक रूप:
ax2 + bx + c = 0
4. Solution by Factorisation Method – गुणनखंड विधि
Steps:
- Write the equation in standard form.
- Factorise the quadratic expression.
- Equate each factor to zero.
- Solve for x.
Example:
x2 − 5x + 6 = 0
(x − 2)(x − 3) = 0
x = 2 or x = 3
5. Completing the Square Method – वर्ग पूर्ण करने की विधि
In this method, the quadratic equation is converted into a perfect square.
Example:
x2 + 6x + 5 = 0
x2 + 6x = −5
(x + 3)2 = 4
x = −1 or x = −5
6. Quadratic Formula – द्विघात सूत्र
For the equation ax2 + bx + c = 0, the solution is:
x = (−b ± √(b2 − 4ac)) / 2a
7. Discriminant – विविक्तांक
The expression b2 − 4ac is called the Discriminant.
D = b2 − 4ac
8. Nature of Roots – मूलों का स्वभाव
The nature of roots of a quadratic equation depends on the value of the discriminant.
9. Relationship between Discriminant and Nature of Roots
| Discriminant (D) | Nature of Roots |
|---|---|
| D > 0 | Two distinct real roots |
| D = 0 | Two equal real roots |
| D < 0 | No real roots |
10. Word Problems based on Quadratic Equations – कथनात्मक प्रश्न
English: Word problems involve forming a quadratic equation from given conditions
and solving it.
Example:
The product of two consecutive positive integers is 132.
Let the integers be x and x + 1
x(x + 1) = 132
x2 + x − 132 = 0
हिंदी: कथनात्मक प्रश्नों में दी गई जानकारी से द्विघात समीकरण बनाकर हल किया जाता है।