Question

Solve the equation. \(|x|=3\)

Short answer

The solutions to the equation \(|x|=3\) are \(x = 3\) and \(x = -3\).

Step-by-step solution

Understand absolute value concept

Understanding the concept of absolute value is paramount. It is the distance of the number from zero, hence it is always positive. So, \(|x|=3\) implies that \(x\) is a distance of 3 units on the number line. This could mean \(x = +3\) or \(x = -3\).

Set \(x\) positive

Setting \(x\) equals to \(+3\) gives \(x = +3\). This is one solution to the equation.

Set \(x\) negative

On the other hand, setting \(x\) equals to \(-3\) gives \(x = -3\). So, this forms the second solution to the equation.

Key concepts

Solving Absolute Value

When faced with an equation that involves the absolute value, it is essential to remember that the absolute value of a number represents its distance from zero on the number line, regardless of direction. Consequently, the equation \( |x| = 3 \) indicates there are two numbers, equal distances from zero, that are solutions. To solve for \( x \) efficiently, one can consider both the positive and negative possibilities that would satisfy the equation.

For instance, since the absolute value of 3 is 3 (\( |3| = 3 \) ), and the absolute value of -3 is also 3 (\( |-3| = 3 \) ), both numbers are viable solutions. Thus, \( x \) can be either 3 or -3. Breaking down the problem into two separate cases, \( x = 3 \) and \( x = -3 \) simplifies the task and reveals the dual solutions to the absolute value equation.

Number Line Representation

A number line is an invaluable tool for visualizing the concept of absolute value and the solutions to an absolute value equation. It's an elongated horizontal line marked with numbers at regular intervals, typically centered around zero, the origin. To represent an absolute value equation on a number line, such as \( |x| = 3 \) , the distance from zero is marked in both the positive and negative directions.

Marking the Solutions

One would place a point on +3 to show the positive distance and another point on -3 to represent the negative distance. This visual aid reinforces the understanding that absolute value indicates a distance without regard to direction. Through this illustration, it becomes clear why equations involving absolute values can have two different numerical solutions.

Positive and Negative Solutions

The concept of absolute value gives rise to a unique scenario where an equation can have both a positive and a negative solution. Unlike most algebraic equations that yield a singular value for \( x \) , absolute value equations often require considering two possible cases. The positive solution is direct—what number itself equals 3? Clearly, \( x = 3 \) is a solution.

For the negative solution, we must ask a different question—what number, when considered without regard to its sign, equals 3? Here, \( x = -3 \) emerges as the second solution because the absolute value of -3 is indeed 3. Acknowledging both the positive and negative solutions is core to the understanding of absolute value equations and expands the repertoire of solutions available in mathematical equations.