Chapter 7: Problem 52
REASONING Determine whether the statement \(\sqrt[4]{(-x)^{4}}=x\) is sometimes, always, or never true.
Short Answer
Expert verified
The statement is sometimes true, specifically for non-negative values of \( x \).
Step by step solution
01
Understand the Expression
We want to determine if the equation \( \sqrt[4]{(-x)^{4}} = x \) holds for different possible values of \( x \). This involves simplifying the left side and analyzing whether it equals the right side (\( x \)).
02
Simplify the Expression
Start by simplifying the expression \( \sqrt[4]{(-x)^{4}} \). Raising \( -x \) to the 4th power results in \( (-x)^{4} = x^{4} \), as any negative number raised to an even power becomes positive. So the expression becomes \( \sqrt[4]{x^{4}} \).
03
Simplify Using Properties of Exponents
The expression \( \sqrt[4]{x^{4}} \) is equivalent to \( (x^{4})^{1/4} = x^{4/4} = x^{1} = x \). Thus, \( \sqrt[4]{(-x)^{4}} = x \) simplifies to \( x \), suggesting the equation holds.
04
Analyze for Different Values of x
Consider both positive and negative values of \( x \). When \( x \) is positive, \( \sqrt[4]{(-x)^{4}} = x \) translates to the expression being true, as both sides equal \( x \). When \( x \) is negative, the left side simplifies to \( -x \), meaning the expression \( (-x)^{4} \) inside the fourth root evaluates to a positive number, resulting also in \( \,|x| \, = \, |x| \). Therefore, the positive outcome should match with the absolute value, triggered for positive \( x \).
05
Verify and Conclude
Re-examining for \( x = 0 \) results in \( \sqrt[4]{(-0)^4} = 0 \), which holds true as well. Thus, to be precise, since the expression fails for negative numbers in terms of equal algebraic direction and holds for \( x = 0 \), the statement is true when \( x \) is non-negative (i.e., positive or zero).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Equation Simplification
Equation simplification is a fundamental step in solving algebraic problems. In this exercise, we're examining the statement \( \sqrt[4]{(-x)^{4}} = x \).
Our goal is to simplify the left side to see if it matches the right side across different values of \( x \). Begin by noting that raising a number to the fourth power and then taking the fourth root is a way of un-doing the power; however, we must consider the nature of \( x \) (whether positive, negative, or zero).
For simplification:
Our goal is to simplify the left side to see if it matches the right side across different values of \( x \). Begin by noting that raising a number to the fourth power and then taking the fourth root is a way of un-doing the power; however, we must consider the nature of \( x \) (whether positive, negative, or zero).
For simplification:
- Raising \( -x \) to the 4th power results in \( x^{4} \), as negative signs vanish when raised to even powers.
- Taking the fourth root of \( x^{4} \) returns \( x \), provided \( x \) is positive or zero.
Properties of Exponents
The properties of exponents play a pivotal role in simplifying expressions like \( \sqrt[4]{(-x)^{4}} \). Understanding these properties allows us to manipulate and simplify expressions effectively.
For the given expression:
For the given expression:
- When we raise \(-x\) to the fourth power \( (-x)^{4} \), it becomes \( x^{4} \) because exponents work by multiplying the base by itself, and even exponents eliminate any negative signs.
- The expression \( \sqrt[4]{x^{4}} \) simplifies to \( (x^{4})^{1/4} \). Using the property \((a^m)^{n} = a^{mn}\), we obtain \( x^{4/4} = x \).
Negative Values in Equations
Handling negative values in algebraic equations requires careful consideration. In our example, we have \( -x \), which can represent a negative number when \( x \) itself is positive.
When simplified:
When simplified:
- The expression \((-x)^{4}\) yields \(x^{4}\), which is positive.
- For negative initial values of \(x\), \((-x)^{4}\) is still \(x^{4}\), which remains positive, showcasing how even powers neutralize negatives.
Even Powers and Positivity
Even powers, such as squaring or taking to the fourth power, have a unique property: they always yield a non-negative result. This concept is critical when dealing with the expression \( \sqrt[4]{(-x)^{4}} \).
Here's what happens:
Here's what happens:
- Any negative number raised to an even power, like two or four, becomes positive. In our exercise, \((-x)^{4} = x^{4}\) due to this property.
- As a result, \(\sqrt[4]{x^{4}} = x\) if \(x\) is positive or zero. This behavior is due to the fact that the root negates the even power but remains positive or zero.