/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 40 Evaluate each expression without... [FREE SOLUTION] | 91Ó°ÊÓ

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Evaluate each expression without using a calculator. $$ (-27)^{-1 / 3} $$

Short Answer

Expert verified
The result is \(-\frac{1}{3}\).

Step by step solution

01

Understanding the Expression

The expression \((-27)^{-1/3}\)involves finding the cube root of -27 and then taking the reciprocal. The exponent \(-\frac{1}{3}\) indicates an operation involving roots and reciprocals.
02

Find the Cube Root

First, we consider what the cube root of \(-27\) is. The cube root of a number is a value that, when multiplied by itself three times, gives the original number. We know that \((-3) \times (-3) \times (-3) = -27\).Therefore, the cube root of \(-27\) is \(-3\).
03

Apply the Reciprocal

Now, we take the reciprocal of the cube root we just found. The cube root of the expression is \(-3\), then the reciprocal (since the exponent is negative) is \(\frac{1}{-3}\) or equivalently \(-\frac{1}{3}\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Understanding Cube Roots
The cube root of a number is the value that, when multiplied by itself three times, results in the original number. For example, if you cube 2 (i.e., multiply 2 by itself twice), you'll get 8. Hence, the cube root of 8 is 2. But how about negative numbers? The cube root can handle these too. Negative numbers also have a real cube root because multiplying an odd number of negative numbers will result in a negative outcome. For instance, \((-3) \times (-3) \times (-3) = -27\). Thus, the cube root of \(-27\) is \(-3\).
This property makes cube roots distinct from square roots, which typically don't produce real results for negatives. So, whenever you encounter a cube root within an expression, remember you're hunting for that special number that, when cubed, gives you the target value.
The Role of Reciprocals
A reciprocal is simply the 'flip' of a number. For any non-zero number \(a\), its reciprocal is \(\frac{1}{a}\). For example, the reciprocal of 4 is \(\frac{1}{4}\) and for \(-3\), it's \(-\frac{1}{3}\). Reciprocals are quite handy in many mathematical operations, especially in division. When you multiply a number by its reciprocal, the result is always 1.
In the context of exponents, if an exponent is negative, it generally signals that a reciprocal needs to be calculated. This is because \(a^{-n} = \frac{1}{a^n}\). Hence, for our original expression \((-27)^{-\frac{1}{3}}\), after identifying \(-3\) as the cube root, we calculate the reciprocal to achieve the final result: \(-\frac{1}{3}\). Understanding reciprocals can greatly demystify expressions with negative exponents.
Demystifying Negative Exponents
Negative exponents might seem confusing at first, but they're quite straightforward once you get the hang of it. When you encounter a negative exponent, it typically means you're dealing with a reciprocal. \(a^{-n} = \frac{1}{a^n}\), so a negative exponent flips the base to its inverse. This move allows us to manage expressions efficiently without changing their core value. For instance, with the expression \((-27)^{-\frac{1}{3}}\), the negative exponent of \(-\frac{1}{3}\) indicates that the reciprocal must be taken. First, you find the cube root, which turns \(-27\) into \(-3\). The presence of a negative exponent means you must flip this to \(-\frac{1}{3}\).
Mastering this concept lets you unravel mathematical expressions adeptly and will make you more confident with exponentiation problems. Remember: a negative exponent tells you to move the base into the denominator! Understanding this concept is crucial for tackling complex mathematical equations with ease.

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