Chapter 1: Problem 3
How many solutions will \(|a x+b|=k\) have for each situation? (a) \(k=0\) (b) \(k>0\) (c) \(k<0\)
Short Answer
Expert verified
(a) 1 solution. (b) 2 solutions. (c) No solution.
Step by step solution
01
Understanding the Abs Value Equation
The given equation is \(|a x + b| = k\). This is an absolute value equation, meaning it expresses the distance of \(a x + b\) from zero on a number line. To solve these equations, we must consider the properties of absolute values: they are always non-negative.
02
Case (a) \(k=0\)
When \(k = 0\), the equation \(|a x + b| = 0\) implies that \a x + b\ must also equal zero, since the distance from zero is zero only at zero. Thus, \(a x + b = 0\). Solving for \(x\), we get \(x = -\frac{b}{a}\). Hence, there is exactly one solution in this case.
03
Case (b) \(k>0\)
When \(k > 0\), the absolute value equation \(|a x + b| = k\) can be split into two linear equations: \(a x + b = k\) and \(a x + b = -k\). Solving these two equations: 1. For \(a x + b = k\), we find \(x = \frac{k - b}{a}\). 2. For \(a x + b = -k\), we find \(x = \frac{-k - b}{a}\). Thus, there are exactly two solutions when \(k > 0\).
04
Case (c) \(k
When \(k < 0\), the equation \(|a x + b| = k\) has no solutions because absolute values cannot be negative. Therefore, there are no solutions in this situation.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Solving Absolute Value Equations
To solve absolute value equations like \(|a x + b| = k\), understanding the nature of absolute value is crucial. An absolute value equation describes the distance of the expression inside the absolute value from zero on a number line.
- When solving equations of the form \(|a x + b| = k\), there are specific steps to take depending on the value of \(k\).
- Case (a): \(k = 0\): When \(k = 0\), the absolute value equation simplifies to \(a x + b = 0\). Solving this, we find \(x = -\frac{b}{a}\), meaning there is only one solution.
- Case (b): \(k > 0\): When \(k\) is positive, we split the equation into two linear equations: \(a x + b = k\) and \(a x + b = -k\). Solving each equation separately gives us two solutions.
- Case (c): \(k < 0\): If \(k\) is negative, there are no solutions. This is because absolute values cannot be negative.
Properties of Absolute Values
Absolute values express the distance from zero, and they are always non-negative. An equation of the form \(|a x + b| = k\) leverages these properties to define specific conditions.
- The absolute value of a number \(x\) is \(x\) if \(x \geq 0\) and \(-x\) if \(x < 0\).
- For example, \(|-3| = 3\) and \( |5| = 5\).
- Absolute value equations, therefore, must be analyzed to ensure the value inside is within the allowed range (non-negative).
- Through these properties, we solve \(|a x + b| = k\) by considering all possible values that the expression \(|a x + b|\) can take.
Linear Equations in Absolute Value Problems
Solving absolute value equations often leads to solving linear equations. Linear equations are equations of the form \(a x + b = c\), where \(a\), \(b\), and \(c\) are constants.
- When \(k = 0\), solving \(|a x + b| = 0\) results in the linear equation \(a x + b = 0\), with one unique solution: \(x = -\frac{b}{a}\).
- When \(k > 0\), the equation \(|a x + b| = k\) splits into two linear equations: \(a x + b = k\) and \(a x + b = -k\). Solving these equations provides two distinct solutions.
- Each linear equation can be solved by isolating \(x\) and simplifying the equation to find the value of \(x\).