Chapter 5: Problem 5
Simplify each expression. Write each result using positive exponents only. $$ \left(-\frac{1}{4}\right)^{-3} $$
Short Answer
Expert verified
The expression simplifies to -64.
Step by step solution
01
Understand the meaning of a negative exponent
Negative exponents indicate that the base is on the opposite side of a fraction. For instance, \[a^{-b} = \frac{1}{a^b}\]. Therefore, \((-\frac{1}{4})^{-3}\) means we need to take the reciprocal of \((-\frac{1}{4})\) to make the exponent positive.
02
Formulate the positive exponent
Taking the reciprocal of \(-\frac{1}{4}\), we get \(-4\). Hence, \[(-\frac{1}{4})^{-3} = (-4)^3.\]
03
Apply exponentiation to the new base
Now calculate \((-4)^3\), which means multiplying -4 by itself three times: \[(-4) \times (-4) \times (-4) = -64.\]
04
Finalize the expression with positive exponents
The expression \((-\frac{1}{4})^{-3}\) simplifies to \[-64\], as it already involves only positive exponents.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Negative Exponents
Negative exponents might seem a little tricky at first, but they have a simple meaning. When you see a negative exponent, it means you need to flip the base to the opposite side of a fraction. This process is done to get a positive exponent. For example,
- If you have a number like \(a^{-b}\), it means that you are actually dealing with the reciprocal of the base raised to a positive exponent: \(\frac{1}{a^b}\).
- \[\left(-\frac{1}{4}\right)^{-3} = \left(-4\right)^3\]
Reciprocal
The concept of a reciprocal is essential when dealing with negative exponents. A reciprocal is just flipping a fraction upside down. For a number expressed as a fraction like \(\frac{1}{4}\), its reciprocal would be \(4\). This is because the numerator and the denominator of the fraction swap places when finding the reciprocal.
For our specific example, we start with \(-\frac{1}{4}\). The reciprocal of \(-\frac{1}{4}\) is \(-4\), because again, you're flipping the fraction upside down. This step changes the negative exponent to a positive one, making it much easier to work with.
For our specific example, we start with \(-\frac{1}{4}\). The reciprocal of \(-\frac{1}{4}\) is \(-4\), because again, you're flipping the fraction upside down. This step changes the negative exponent to a positive one, making it much easier to work with.
- Reciprocal of \(-\frac{1}{4}\) is \(-4\)
- Using this reciprocal turns \((-\frac{1}{4})^{-3}\) into \((-4)^3\)
Positive Exponents
After you've turned a negative exponent into a positive one, working with positive exponents becomes much easier and more straightforward. Positive exponents tell us how many times a number (base) is multiplied by itself.
Using the reciprocal process explained, the initial expression \((-\frac{1}{4})^{-3}\) becomes \((-4)^3\) with a positive exponent. Now you simply multiply the base \(-4\) by itself the number of times indicated by the exponent, which in this case is 3.
Using the reciprocal process explained, the initial expression \((-\frac{1}{4})^{-3}\) becomes \((-4)^3\) with a positive exponent. Now you simply multiply the base \(-4\) by itself the number of times indicated by the exponent, which in this case is 3.
- The calculation is as follows: \[(-4) \times (-4) \times (-4) = -64\]
Simplification
Simplification is all about making an expression easier to understand and use, often by reducing it to its most basic form. In the context of exponents, this means expressing a number without unnecessary complexity, such as negative exponents or fractions that can be simplified.
In the previous steps, we turned \((-\frac{1}{4})^{-3}\) into \((-4)^3\), and then calculated it as \(-64\). There's nothing left to simplify because we have a single, whole number with a positive exponent.
In the previous steps, we turned \((-\frac{1}{4})^{-3}\) into \((-4)^3\), and then calculated it as \(-64\). There's nothing left to simplify because we have a single, whole number with a positive exponent.
- Simplifying exponents often means turning negative exponents into positive ones.
- It also involves reducing fractions or expressions to their simplest form.
- The result should typically be a clearer, more straightforward expression.