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Quadratic Formula

from class:

Intermediate Algebra

Definition

The quadratic formula is a mathematical equation used to solve quadratic equations, which are polynomial equations of the form $ax^2 + bx + c = 0$, where $a$, $b$, and $c$ are real numbers and $a \neq 0$. This formula provides a systematic way to find the solutions, or roots, of a quadratic equation.

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5 Must Know Facts For Your Next Test

  1. The quadratic formula is $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$, where $a$, $b$, and $c$ are the coefficients of the quadratic equation $ax^2 + bx + c = 0$.
  2. The quadratic formula is used to solve quadratic equations when other methods, such as factoring or completing the square, are not applicable.
  3. The discriminant, $b^2 - 4ac$, determines the nature of the roots of a quadratic equation: if the discriminant is positive, the equation has two real roots; if the discriminant is zero, the equation has one real root; if the discriminant is negative, the equation has two complex roots.
  4. Quadratic equations can be used to model a variety of real-world situations, such as the motion of an object under the influence of gravity or the growth of a population over time.
  5. The quadratic formula is a fundamental tool in solving equations in quadratic form, which are equations that can be rearranged to the form $ax^2 + bx + c = 0$.

Review Questions

  • Explain how the quadratic formula is used to solve a quadratic equation.
    • The quadratic formula is used to solve a quadratic equation of the form $ax^2 + bx + c = 0$ by substituting the values of $a$, $b$, and $c$ into the formula $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$. This formula provides the two solutions, or roots, of the equation. If the discriminant, $b^2 - 4ac$, is negative, the roots will be complex numbers; if the discriminant is zero, the equation has one real root; and if the discriminant is positive, the equation has two real roots.
  • Describe the relationship between the quadratic formula and the process of completing the square.
    • The quadratic formula is derived from the process of completing the square. Completing the square involves rearranging a quadratic equation to the form $(x - h)^2 = k$, where $h$ and $k$ are constants. This process leads to the quadratic formula, which provides a systematic way to solve quadratic equations without the need for completing the square manually. The quadratic formula incorporates the coefficients $a$, $b$, and $c$ of the original quadratic equation, allowing for a more efficient and generalized approach to solving these types of equations.
  • Analyze how the quadratic formula can be used to solve equations in quadratic form, and explain the significance of this application.
    • The quadratic formula can be used to solve equations in quadratic form, which are equations that can be rearranged to the standard form of a quadratic equation, $ax^2 + bx + c = 0$. By identifying the values of $a$, $b$, and $c$ in the equation, the quadratic formula can be applied to find the solutions, or roots, of the equation. This is particularly useful when dealing with equations that cannot be easily factored or solved using other methods, such as the square root property or completing the square. The ability to solve equations in quadratic form expands the range of problems that can be tackled using the quadratic formula, making it a powerful tool in various mathematical and scientific applications.
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