Question

Evaluate the expression for the given value of the variable. $$b-12 \text { when } b=43$$

Short answer

The evaluated result of the expression \(b-12\) when \(b=43\) is \(31\).

Step-by-step solution

Substitute the given value

Substitute \(43\) for \(b\) in the expression \(b-12\), so the new expression is \(43-12\).

Perform the operation

After substituting, subtract the value of \(12\) from \(43\) to evaluate the expression.

Key concepts

Substitution

Understanding the process of substitution is essential when working with algebraic expressions. Substitution involves replacing a variable with a given value. In the context of algebra, a variable is a symbol that represents an unknown number, often denoted by letters such as x, y, or b. When a problem asks you to evaluate an expression for a defined value of this variable, you replace the variable with the indicated number.

For example, given the expression b-12 and told that b equals 43, you would substitute 43 for every instance of b in the expression, just as seen in the original exercise. This results in a new expression, 43-12, that no longer contains the variable and is ready for the next step, which is performing the required arithmetic operation.

Importance of Substitution

Substitution is not only a cornerstone of algebra but also a frequent necessity across numerous fields of mathematics. Through substitution, you can simplify complex formulas, solve equations, and even understand functions better by seeing how they behave with specific values.

Algebraic Expressions

An algebraic expression is a mathematical phrase that includes numbers, variables, and operation symbols. In our example, b-12 is an algebraic expression with b as the variable and -12 as a constant that signifies a number to be subtracted from the variable's value. There are no equality signs (=) in algebraic expressions, distinguishing them from equations.

Working with such expressions often requires you to perform various operations following order of operations. However, the expression b-12 is simple enough that it only entails one operation once a value is substituted for b.

Components of Algebraic Expressions

• Constants: Numbers on their own, like 12 in our expression, are known as constants.
• Variables: Symbols like b stand in for unknown numbers or numbers that can change.
• Operations: These are mathematical instructions like addition, subtraction, multiplication, and division that indicate what to do with the constants and variables.

Arithmetic Operations

The final step in evaluating an algebraic expression after substitution is performing the necessary arithmetic operations. As we saw in the exercise, after substituting the variable with a number, we are left with the basic arithmetic task of 43-12. Arithmetic operations are straightforward and include addition, subtraction, multiplication, and division.

In this instance, we are dealing with subtraction. When performing arithmetic operations, it's essential to follow the correct order if multiple operations are present, but in our example, there's only one operation to perform. It's as simple as subtracting 12 from 43 to get the answer, which is 31.

Significance of Arithmetic Operations

These operations are the building blocks for more complex mathematics. They are used in everyday life for tasks such as budgeting, calculating distances, or even determining the time it takes to travel somewhere. Mastering arithmetic operations is fundamental to progressing in mathematics and handling everyday numerical problems.