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Ch. 3 - Polynomial and Rational Functions
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Non è quello che usi tu?Cambia libro di testo
Capitolo 4, Problema 82

Exercises 82–84 will help you prepare for the material covered in the next section. Solve: x2+4x−1=0

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1
Identify the type of equation given. Here, the equation x2 + 4x - 1 = 0 is a quadratic equation because it is a polynomial of degree 2.
Recall the quadratic formula, which is used to solve any quadratic equation of the form ax^2 + bx + c = 0. The formula is x = \(\frac{-b \pm \sqrt{b^2 - 4ac}\)}{2a}.
Determine the coefficients from the equation: a = 1, b = 4, and c = -1.
Substitute the values of a, b, and c into the quadratic formula: x = \(\frac{-4 \pm \sqrt{4^2 - 4(1)(-1)}\)}{2(1)}.
Simplify the expression under the square root (the discriminant) and then simplify the entire expression to find the two possible values of x.

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Quadratic Equations

A quadratic equation is a second-degree polynomial equation in the form ax² + bx + c = 0, where a ≠ 0. It represents a parabola when graphed and can have zero, one, or two real solutions depending on the coefficients.
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Introduction to Quadratic Equations

Quadratic Formula

The quadratic formula x = (-b ± √(b² - 4ac)) / (2a) provides the solutions to any quadratic equation ax² + bx + c = 0. It uses the coefficients a, b, and c to find the roots, including complex solutions if the discriminant is negative.
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Solving Quadratic Equations Using The Quadratic Formula

Discriminant

The discriminant, given by b² - 4ac, determines the nature of the roots of a quadratic equation. If positive, there are two distinct real roots; if zero, one real root; and if negative, two complex conjugate roots.
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The Discriminant