Problem 44 - Algebra 1

Question

Rewrite the expression with positive exponents $$\frac{1}{(4 x)^{-5}}$$

Step-by-Step Solution

Answer

The expression \(\frac{1}{(4 x)^{-5}}\) rewritten with positive exponents is \((4x)^5\).

Step 1: Identify the term with a negative exponent

In our expression, \((4x)^{-5}\) is the term with a negative exponent - this is the term we want to rewrite so the exponent is positive.

Step 2: Apply the rules of exponents

One of the fundamental rules of exponents is that \( a^{-n} = \frac{1}{a^n} \). We can apply this rule to our expression to change the negative exponent to a positive exponent. Hence, \((4x)^{-5} = \frac{1}{(4x)^5}\). The expression now becomes \(\frac{1}{\frac{1}{(4x)^5}}\).

Step 3: Simplify the expression

In mathematics, \(\frac{a}{\frac{b}{c}}\) is equivalent to \(a \cdot \frac{c}{b}\). So we can simplify our expression to \((4x)^5\).

Key Concepts

Understanding Negative Exponents

Negative exponents might seem a bit intimidating at first, but they're actually quite straightforward once you get the hang of it. A negative exponent indicates that the base should be on the opposite side of the fraction line. Specifically, any nonzero number (like \( a \)) raised to a negative exponent (\( -n \)) is equal to one over that number raised to the positive exponent (\( n \)).

Let's break it down:

• \( a^{-n} = \frac{1}{a^n} \)

This means that when you see a negative exponent, you simply take the reciprocal of the base raised to the opposite positive exponent. It's like flipping the base to the denominator if it originally was in the numerator, or vice versa. This rule is incredibly useful when rewriting expressions to eliminate negative exponents.

Grasping Positive Exponents

Positive exponents are more familiar, and they signify straightforward multiplication. When you have \( a^n \), it means you multiply \( a \) by itself \( n \) times.

Here’s how it works:

• \( a^2 = a \times a \)
• \( a^3 = a \times a \times a \)
• \( a^n = a \times a \times \, ... \, \times a \); \( n \) times

The rules for operations with exponents apply regardless if they're positive or negative. This understanding helps simplify more complex expressions by combining like terms efficiently. Positive exponents are essential for turning any pre-simplified expression into a readable and clear format.

Simplifying Expressions with Exponents

Simplifying expressions, especially those with exponents, is about making them as simple and clear as possible. Once the negative exponent in an expression is rewritten into a positive one, you often get a clearer result.

For example, let's consider the expression from our exercise:

• We began with \( \frac{1}{(4x)^{-5}} \).
• Using the rule for negative exponents, we rewrite it as \( \frac{1}{\frac{1}{(4x)^5}} \).
• Simplifying the nested fraction results in \( (4x)^5 \).

The process involves recognizing when you can take inverses, moving terms inside a fraction line up or down accordingly. By writing expressions with only positive exponents, you not only simplify the expression but also make it easier to evaluate or further manipulate if necessary. Simplifying expressions into a form with positive exponents is often the final desired state for ease of calculation and clarity.