Chapter 4: Problem 73
Solve by factoring. $$ x^{2}-12 x+20=0 $$
Short Answer
Expert verified
The solutions are \(x = 2\) and \(x = 10\).
Step by step solution
01
Identify a Quadratic Equation
The given equation is in the form of a quadratic equation, which can be written as \( ax^2 + bx + c = 0 \). Here, \( a = 1 \), \( b = -12 \), and \( c = 20 \).
02
Set Up Factoring
To solve the equation by factoring, we need to find two numbers that multiply to \( c \) (which is 20) and add up to \( b \) (which is -12).
03
Find the Numbers
The numbers that multiply to 20 and add up to -12 are -2 and -10. This is because \((-2) \times (-10) = 20\) and \((-2) + (-10) = -12\).
04
Write the Factored Equation
Using the numbers from the previous step, we can rewrite the equation as \((x - 2)(x - 10) = 0\).
05
Solve for x
Set each factor equal to zero: 1. \(x - 2 = 0\) which gives \(x = 2\) 2. \(x - 10 = 0\) which gives \(x = 10\).
06
Verify the Solutions
To confirm, substitute \(x = 2\) and \(x = 10\) back into the original equation. Both values satisfy \(x^2 - 12x + 20 = 0\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Factoring Method
The factoring method is a classic approach to solving quadratic equations. A quadratic equation is typically in the form \( ax^2 + bx + c = 0 \). The core idea of factoring involves expressing the quadratic expression as a product of two binomials. This allows you to find the solutions by solving simpler linear equations.
Here's how the factoring method works:
Here's how the factoring method works:
- First, identify the coefficients \( a \), \( b \), and \( c \) from the quadratic equation.
- Next, look for two numbers that multiply to \( c \) and add up to \( b \). These numbers are crucial because they help break the equation into simpler parts.
- Rewrite the quadratic equation as a product of these two binomial expressions.
- Finally, solve each binomial equation by setting it equal to zero and solving for \( x \). This will give you the roots of the equation.
Quadratic Formula
The quadratic formula is a universal tool that provides a straightforward way to find the roots of any quadratic equation, even if the equation is difficult to factor. The general form of a quadratic equation is \( ax^2 + bx + c = 0 \), and the quadratic formula is:\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]
Here's a breakdown of how to use the quadratic formula:
Here's a breakdown of how to use the quadratic formula:
- First, ensure the equation is in standard form \( ax^2 + bx + c = 0 \).
- Identify the values of \( a \), \( b \), and \( c \).
- Calculate the discriminant \( b^2 - 4ac \). The discriminant tells us about the nature of the roots.
- If it's positive, there are two real and distinct roots.
- If it's zero, there is exactly one real root (a repeated root).
- If it's negative, there are no real roots, but there are two complex roots.
- Substitute \( a \), \( b \), and \( c \) into the quadratic formula to find the roots.
Roots of Quadratic Equations
The roots of a quadratic equation are the values of \( x \) for which the equation \( ax^2 + bx + c = 0 \) has a value of zero. These roots are where the graph of the quadratic equation crosses the x-axis. Finding these roots is essential as they reveal crucial information about the equation's solutions.
There are three main methods to find the roots of quadratic equations:
There are three main methods to find the roots of quadratic equations:
- Factoring: As mentioned, this involves rewriting the quadratic equation into a product of two binomials, then solving for \( x \).
- Quadratic Formula: This is used when the equation is difficult to factor, ensuring that you can always solve the equation.
- Completing the Square: A method where the equation is manipulated to form a perfect square trinomial, allowing you to solve for \( x \) directly.