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Quadratic Equation

Quadratic Equation

One-page printable reference

See It in Action

Two examples of the idea done right—and one common look-alike that is not right.

EXAMPLE

EXAMPLE

NON-EXAMPLE

Definition

A quadratic equation is an equation of the second degree (its highest exponent is 2) with a standard form that can be written:


ax^2 + bx + c = 0


where a, b, and c are constants, and a does not equal 0 (if a = 0), the equation is not quadratic, but linear). The variable x is raised to the second power, which is why it's called a quadratic equation.

Key characteristics of quadratic equations:

  1. Degree: The highest exponent of x is 2.

  2. Standard form: The equation is typically written in the form ax^2 + bx + c = 0, where a, b, and c are real numbers, and a does not equal 0.

  3. Solutions: Quadratic equations can have two, one or zero solutions, which may be real or complex, depending on the discriminant (b^2 - 4ac).

Example:

The equation 2x^2 + 3x - 5 = 0 is a quadratic equation, where:

  • a = 2

  • b = 3

  • c = -5


Quadratic equations can be solved using methods like factoring, completing the square, or using the quadratic formula.

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