Chapter 5: Problem 12
In \(3-14,\) use the quadratic formula to find the imaginary roots of each equation. $$ x^{2}+5=4 x $$
Short Answer
Expert verified
The imaginary roots are \( x = 2 + i \) and \( x = 2 - i \).
Step by step solution
01
Write the Equation in Standard Form
First, we need to rewrite the quadratic equation given in the standard form, which is \( ax^2 + bx + c = 0 \). The original equation is \( x^2 + 5 = 4x \). Subtract \( 4x \) from both sides to get \( x^2 - 4x + 5 = 0 \).
02
Identify the Coefficients
Now that we have the quadratic equation in the form \( ax^2 + bx + c = 0 \), identify the coefficients: \( a = 1 \), \( b = -4 \), and \( c = 5 \).
03
Use the Quadratic Formula
The quadratic formula is given by \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \). Substitute the values of \( a \), \( b \), and \( c \) into the formula: \( x = \frac{-(-4) \pm \sqrt{(-4)^2 - 4 \cdot 1 \cdot 5}}{2 \cdot 1} \).
04
Simplify the Expression
Calculate inside the square root: \( (-4)^2 = 16 \) and \( 4 \cdot 1 \cdot 5 = 20 \). This gives us \( x = \frac{4 \pm \sqrt{16 - 20}}{2} \), or \( x = \frac{4 \pm \sqrt{-4}}{2} \).
05
Solve for Imaginary Roots
The square root of \(-4\) is an imaginary number: \( \sqrt{-4} = 2i \). So, our equation becomes \( x = \frac{4 \pm 2i}{2} \). Simplifying this gives us the solutions: \( x = 2 + i \) and \( x = 2 - i \).
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Imaginary Roots
When you encounter a quadratic equation and need to find its roots, you might discover that they can be imaginary. Imaginary roots occur when the discriminant of a quadratic equation is negative. In the quadratic formula, the discriminant is the part under the square root: \(b^2 - 4ac\).
In our example, the discriminant \(16 - 20\) equals \(-4\). This negative value means that the square root involves an imaginary number. Imaginary numbers use "\(i\)," where \(i\) is the square root of \(-1\).
Some key points to remember about imaginary roots:
In our example, the discriminant \(16 - 20\) equals \(-4\). This negative value means that the square root involves an imaginary number. Imaginary numbers use "\(i\)," where \(i\) is the square root of \(-1\).
Some key points to remember about imaginary roots:
- Imaginary numbers are paired with real numbers when forming solutions. These are also called complex numbers.
- Imaginary roots often occur as conjugates, which means if \(x = a + bi\) is a root, \(x = a - bi\) is the other root.
- They help represent roots that cannot be placed on the traditional number line.
Standard Form Quadratic Equation
A quadratic equation is any equation that can be represented in the form \(ax^2 + bx + c = 0\). This is called the standard form. It's a structured way to write a quadratic equation which is essential when applying the quadratic formula to find roots.
The standard form makes it easy to identify:
The standard form makes it easy to identify:
- "\(a\)" as the coefficient of \(x^2\), determining the parabola's opening direction and width.
- "\(b\)" as the coefficient of \(x\), influencing the symmetry of the parabola.
- "\(c\)" as the constant term, impacting the y-intercept.
Complex Numbers
Complex numbers are extensions of the real number system, incorporating imaginary numbers. They take the form \(a + bi\), where \(a\) and \(b\) are real numbers, and \(i\) represents the square root of \(-1\). In quadratic equations, complex numbers frequently appear as solutions when the discriminant is negative, as seen in our example.
Important attributes of complex numbers include:
Important attributes of complex numbers include:
- The real part is the "\(a\)" term, and the imaginary part is the "\(b\)" term.
- The "\(i\)" stands for an imaginary unit, which is fundamental in describing numbers not found on the traditional number line.
- Complex conjugates are used in solutions like \(x = 2 + i\) and \(x = 2 - i\), ensuring the quadratic equation's solutions are comprehensive.