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Substitution is a key component of evaluating expressions in algebra. It means replacing the variables in an expression with their given values. This step allows us to manipulate and solve the expression more easily. For example, in the problem provided, we have the values: \(x = 2\), \(y = -3\), and \(z = -4\). To evaluate the expression \(-z\), we substitute the value of \(z\) with \(-4\), so the expression becomes \(-(-4)\).

It's important to carefully substitute each variable with its corresponding value and ensure accuracy during this process. Mistakes often occur if we misread or misplace a number.

Algebraic expressions are combinations of variables, numbers, and operations like addition, subtraction, multiplication, and division. These expressions allow us to represent real-world situations mathematically. In our given exercise, the algebraic expression is \(-z\), which is a simplified form but contains valuable information.

Understanding algebraic expressions is crucial because they form the foundation for more complex algebraic equations and functions. Mastery of these basic expressions will make it easier to handle more advanced topics in algebra.

Simplification is the process of reducing an algebraic expression to its simplest form. This usually involves performing arithmetic operations and combining like terms. Simplification makes expressions easier to understand and work with.

In the provided exercise, after substituting \(z\) with \(-4\), we get \(-(-4)\). According to the rules of arithmetic, a negative sign before a parenthesis with another negative sign results in a positive value. Therefore, \(-(-4)\) simplifies to \(4\).

Simplification helps us reach the final answer more efficiently and accurately. Always ensure every step is double-checked for correctness, ensuring the final simplified expression truly represents the intended value.