Chapter 1: Problem 37
Solve the equation by factoring. $$x^{2}+x-12=0$$
Short Answer
Expert verified
The solutions are \(x = -4\) and \(x = 3\).
Step by step solution
01
Write Down Quadratic Equation
The given equation is \(x^2 + x - 12 = 0\). We need to solve this by factoring.
02
Identify Two Numbers
Find two numbers whose product is \(-12\) (the constant term) and whose sum is \(1\) (the coefficient of \(x\)). These numbers are \(4\) and \(-3\) because \(4\times(-3) = -12\) and \(4 + (-3) = 1\).
03
Write the Expression in Factored Form
Use the numbers found to rewrite the quadratic expression as \((x + 4)(x - 3)\). Thus, the equation becomes \((x + 4)(x - 3) = 0\).
04
Solve Each Factor for Zero
Set each factor equal to zero. So, solve the equations \(x + 4 = 0\) and \(x - 3 = 0\).
05
Solve for x
For \(x + 4 = 0\), subtract \(4\) from both sides to get \(x = -4\). For \(x - 3 = 0\), add \(3\) to both sides to get \(x = 3\).
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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 powerful technique for solving quadratic equations. It's like solving a puzzle where you break down the expression into simpler pieces. In a standard quadratic equation, of the form \( ax^2 + bx + c = 0 \), here's how the method works:
- First, we look for two numbers that multiply together to give the constant term, \( c \), and at the same time add up to the coefficient of the \( x \) term, \( b \).
- In our exercise, the equation is \( x^2 + x - 12 = 0 \).
- Here, we need two numbers that multiply to \(-12\) (constant term) and add to \(1\) (coefficient of \( x \)).
- These numbers turn out to be \( 4 \) and \(-3 \).
- Once found, these numbers allow us to express the quadratic in its factored form, which looks like \((x + a)(x - b) = 0\).
Roots of Equations
The roots of a given equation are the values of \( x \) that make the equation true. For quadratic equations, these roots are also known as solutions or zeros.
- When the equation is factored, as in our example \((x + 4)(x - 3) = 0\), determining the roots becomes more straightforward.
- The principle we use is that if a product of two terms equals zero, then at least one of these terms must be zero.
- Thus, we set each factor of the product equal to zero separately, leading to \( x + 4 = 0 \) and \( x - 3 = 0 \) in our case.
- Solving these simple linear equations gives us the roots of the quadratic equation, which in this example are \( x = -4 \) and \( x = 3 \).
Solving Quadratic Equations
Solving quadratic equations can be likened to uncovering the secret numbers that satisfy the equation for given values of \( x \). The steps are consistent but require attention to detail.
- Identify the quadratic equation you need to solve. It generally takes the form \( ax^2 + bx + c = 0 \).
- Choose an appropriate method: factoring, using the quadratic formula, or completing the square are common ways.
- In our exercise, we used the factoring method to simplify \( x^2 + x - 12 = 0 \) into \((x + 4)(x - 3) = 0\).
- This approach transforms the problem into solving simpler equations that lead directly to the solutions.
- After factoring, tackle each term independently to find the values of \( x \).