Chapter 0: Problem 104
Solve the quadratic equation by the method of your choice. $$9-6 x+x^{2}=0$$
Short Answer
Expert verified
The quadratic equation \(9-6 x+x^{2}=0\) has only one distinct solution, which is \(x = 3\).
Step by step solution
01
Rearrange to Standard Form
The standard form of a quadratic equation is \(a x^2 + bx + c = 0\). So, rearrange the equation \(9-6 x+x^{2}=0\) to standard form, which is \(x^{2}-6x+9=0\) with \(a = 1\), \(b = -6\), and \(c = 9\)
02
Apply the Quadratic Formula
The quadratic formula is \((-b±\sqrt{b^2-4ac})/2a\). Apply this formula by substituting \(a = 1\), \(b = -6\), and \(c = 9\). This yields two roots, \(x1\) and \(x2\), calculated as follows: \(x1 = (-(-6) + \sqrt{(-6)^2 - 4*1*9}) / (2*1)\) and \(x2 = (-(-6) - \sqrt{(-6)^2 - 4*1*9}) / (2*1)\). Simplified, this results in \(x1 = x2 = 3\)
03
Interpret the Solution
Since the solutions are the same, it means that the quadratic equation has only one distinct root, which in this case, is \(x = 3\). This also signifies that the graph of the quadratic equation will touch the x-axis at one point only, at \(x = 3\)
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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 solutions (or "roots") of any quadratic equation—standard form or not. It provides a straightforward method for calculating the roots regardless of whether they are real or complex numbers. Here is what the formula looks like: \[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]
- The symbol \( \pm \) indicates there could be two solutions for \( x \), one involving addition and the other involving subtraction.
- \( a \), \( b \), and \( c \) are coefficients from the standard form of the quadratic equation \( ax^2 + bx + c = 0 \).
- This formula originates from the process of completing the square, a method used to solve quadratics by transforming them into a perfect square trinomial.
Standard Form of a Quadratic Equation
Before solving a quadratic equation, it must be in standard form, which is written as \( ax^2 + bx + c = 0 \). This structure is important as it prepares the equation for various solution methods, such as factoring, completing the square, or using the quadratic formula. Here’s a breakdown:
- \( a \) is the coefficient of the \( x^2 \) term. It must not be zero to ensure the equation is quadratic.
- \( b \) is the coefficient of the \( x \) term. It can be zero, in which case the equation becomes a simple square.
- \( c \) is the constant term. It can shift the graph of the equation up or down.
Roots of a Quadratic Equation
The roots of a quadratic equation are the values of \( x \) that make the equation true, effectively providing points where the graph of the equation intersects the x-axis. Understanding roots is crucial since:
- When you use the quadratic formula, you find these roots as solutions to the equation.
- There can be two distinct roots, one repeated root (resulting from perfect squares), or complex roots (when discriminant \( b^2 - 4ac \) is negative).