Problem 74 - Introductory and Intermediate Algebra for College Students 4th

Question

Explain how to solve the equation \(-x=-50\)

Step-by-Step Solution

Answer

The solution to the equation \(-x = -50\) is \(x = 50\).

Step 1: Setup

The original equation is given as \(-x=-50\). The aim is to isolate \(x\) and thus resolve its value.

Step 2: Apply the Multiplication Rule

Let's multiply both sides of the equation by -1. This is done so as to eliminate the negative sign in front of \(x\). Doing so, gives us \(x=50\).

Step 3: Conclusion

Thus, we have successfully solved the equation and found that \(x = 50\).

Key Concepts

Isolation of Variables

When solving linear equations, one of the most fundamental goals is to isolate the variable in question. This means we want to get the unknown all by itself on one side of the equation, ideally with a coefficient of 1. In the exercise \( -x=-50 \), the variable \( x \) is already on its own on one side of the equation, but it's accompanied by a negative coefficient. Here, isolation of variables involves getting rid of this negative sign to find the true value of \( x \).

Understanding this concept is essential because it's the heart of algebra. It involves moving terms from one side of the equation to the other, or changing the signs of terms to achieve balance. The process requires a series of inverse operations that can include addition, subtraction, multiplication, and division. The approach ensures that whatever is done to one side of the equation is also done to the other side, maintaining the balance of the equation.

Multiplication Rule

The multiplication rule is a pivotal tool in algebra, particularly when dealing with equations. It states that you can multiply (or divide) both sides of an equation by the same non-zero number without changing the solution to the equation. This rule is crucial when we want to eliminate fractions or clear out coefficients, especially ones that are negative, as we saw in our exercise.

For example, with the equation \( -x = -50 \), by applying the multiplication rule and multiplying by -1, we change the sign of both sides, resulting in \( x = 50 \). This rule is the trusted way to preserve the equality and get the variable by itself. It enables students to simplify equations and make the variable's coefficient positive, which is usually easier to understand and work with during further calculations.

Negative Coefficients

Dealing with negative coefficients in linear equations can be a bit confusing. A negative coefficient simply means that the variable is subtracted from, rather than added to, any other terms. In the exercise \( -x=-50 \), the coefficient \( -1 \) indicates a negative amount of \( x \).

When you encounter a negative coefficient in front of a variable, your aim is to turn it positive because this typically makes for easier interpretation. This is done by multiplying by -1, as negative times negative gives you a positive. This operation is crucial because it doesn't alter the essence of the equation—it simply changes the sign, making it more straightforward to comprehend. Afterwards, it becomes clearer: just as \( -1 \times -50 \) is 50, \( -1 \times x \) becomes simply \( x \) with the negative sign eliminated.