Chapter 5: Problem 153
Solve the equation. Round your answer to three decimal places, if necessary. $$x^{2}-2 x-5=0$$
Short Answer
Expert verified
The solutions are \(x \approx 3.449\) and \(x \approx -1.449\).
Step by step solution
01
Identify the components of the quadratic formula
The quadratic equation is in the form \(ax^{2}+bx+c=0\). In this case, \(a=1\), \(b=-2\), and \(c=-5\).
02
Substitute the values into the quadratic formula
Substitute the values of \(a\), \(b\), and \(c\) into the quadratic formula. We get \(x=\frac{-(-2) \pm \sqrt{(-2)^{2}-4*1*(-5)}}{2*1}\). Which simplifies to \(x=\frac{2 \pm \sqrt{4+20}}{2}\). Therefore, \(x=\frac{2 \pm \sqrt{24}}{2}\). Further simplifying, \(x=\frac{2 \pm 2\sqrt{6}}{2}\) or \(x=1 \pm \sqrt{6}\).
03
Calculate numerical solutions
Now calculate the numerical solutions and round to three decimal places if necessary. We get that \(x=1+ \sqrt{6}\) is approximately \(3.449\) and \(x=1- \sqrt{6}\) is approximately \(-1.449\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Formula
The quadratic formula is a powerful tool used to find the roots of any quadratic equation. A quadratic equation is any polynomial equation of the form \( ax^2 + bx + c = 0 \). Here, \( a \), \( b \), and \( c \) are constants with \( a eq 0 \). The quadratic formula itself is given by: \[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\] This formula helps us find the solutions, also known as the roots, of the quadratic equation. It works for every possible case: whether the equation has two real roots, one real root (when they are identical), or two complex roots. This is determined by the discriminant \( b^2 - 4ac \), which is the part under the square root in the formula.
- If the discriminant is positive, the equation has two distinct real roots.
- If it is zero, there is one real root, repeated.
- If it is negative, the roots are complex and occur as a conjugate pair.
Roots of Quadratic Equation
The roots, or solutions, of a quadratic equation are the values of \( x \) that make the equation \( ax^2 + bx + c = 0 \) true. These roots can be real or complex numbers depending on the equation. The process of finding these roots often involves determining the discriminant \( b^2 - 4ac \) first, as it indicates the nature of the roots:
- Two Real Roots: When the discriminant is positive, it means the parabola described by the equation intersects the x-axis at two points.
- One Real Root: When the discriminant is zero, the parabola just touches the x-axis at one point, also known as a double or repeated root.
- Complex Roots: When the discriminant is negative, the parabola does not intersect the x-axis. The roots are complex numbers that come in conjugate pairs.
Solving Quadratic Equations
Solving quadratic equations is a fundamental skill in algebra, required for understanding various mathematical and real-world problems. One common approach is using the quadratic formula, which provides a direct path to finding the equation's roots. Let's explore the steps involved: 1. **Identify Coefficients:** Start by identifying the values of \( a \), \( b \), and \( c \) in your quadratic equation. You'll need these values to apply the formula.2. **Apply the Quadratic Formula:** Substitute the coefficients into the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \) to calculate the solutions.3. **Simplify the Expression:** Simplify the expression under the square root (discriminant) and continue simplifying the entire formula to solve for the values of \( x \).4. **Interpret the Solutions:** Finally, interpret the solutions based on the discriminant: - Calculate and approximate the roots to the desired decimal places if required. - Use these solutions to understand where the function graph intersects the x-axis. By following these steps systematically, you can solve any quadratic equation efficiently, whether for homework, tests, or real-life applications. Understanding the quadratic formula and its use is key to mastering quadratic equations.