Problem 53 - Algebra and Trigonometry Real Mathematics, Real People

Question

Simplify the expression. $$5-e^{\ln \left(x^{2}+1\right)}$$

Step-by-Step Solution

Answer

The simplified form of the given expression \(5-e^{\ln \left(x^{2}+1\right)}\) is \(4 - x^{2}\).

Step 1: Start

Consider the expression \(5-e^{\ln \left(x^{2}+1\right)}\).

Step 2: Apply the rule \(e^{ln(a)} = a\).

Here we can apply the rule that says: if you have \(e^{\ln(a)}\), that just equals to \(a\). Using this rule we can simplify: \(5-e^{\ln \left(x^{2}+1\right)} = 5 - (x^{2}+1)\).

Step 3: Simplify

Simplifying the expression we have \(5 - x^{2} - 1 -> 4 - x^{2}\).

Key Concepts

Exponential and Logarithmic Functions

Exponential and logarithmic functions are mathematical operations that are intricately related. These functions work as inverses of each other, meaning they can effectively 'undo' each other's operations. In simpler terms, if you apply an exponential function to a variable and then apply a logarithm to the result (or vice versa), you will end up back with the original variable.

When dealing with natural logarithms, denoted by \( \ln \), coupled with the base of natural logarithms \( e \), we often encounter the rule: \( e^{\ln(a)} = a \). This tells us when the exponential function has a logarithm in its exponent, they cancel out, simplifying to just \( a \).

• Example: \( e^{\ln(x^{2}+1)} = x^{2} + 1 \)
• This rule is essential in reducing complex-looking algebraic expressions to simpler forms.

Simplification Rules

Simplification rules in algebra help break down complex expressions into simpler, more manageable forms. These rules involve mathematical operations like addition, subtraction, multiplication, and division. Simplification rules are based on properties of numbers and their operations.

A core principle is to systematically replace complex components with simpler equivalents through standard algebraic transformations, such as:

• Combining like terms: Grouping and simplifying terms that have the same variable or exponent.
• Applying operation rules: For example, simplifying \( e^{\ln(a)} \) using the property \( e^{\ln(a)} = a \).
• Following the order of operations: Ensuring calculations are done in the correct sequence (PEMDAS/BODMAS).

In the provided exercise, the expression \( 5-e^{\ln(x^{2}+1)} \) seems complex initially, but by applying the simplification rule of \(e^{\ln(a)} = a\), it reduces to \( x^{2} + 1 \). Afterward, the expression further simplifies to \( 4 - x^{2} \) as you combine like terms.

Algebraic Expressions

Algebraic expressions are combinations of variables, numbers, and operation symbols. They are the backbone of algebra, allowing us to represent general quantities and relationships.

In an expression like \(5 - e^{\ln(x^{2}+1)}\), each component has a role. The constants (\(5\), the numerical parts) are stable elements, while the variable components (\(x^2\), \(e^{ln(...)}\)) introduce flexibility by allowing to represent a range of values.

• Constants: These are fixed values that do not change.
• Variables: Symbols representing numbers that can vary, e.g., \(x\).
• Operations: Mathematical symbols that show relationships or operations between terms, e.g., addition \(+\), subtraction \(-\).

When simplifying algebraic expressions, our goal is to make them as straightforward as possible by utilizing known mathematical properties and identities. This often involves reducing complexity by combining like terms or using properties of numbers and operations.