Chapter 5: Problem 5
Simplify the expression without a calculator $$ -2(27)^{2 / 3} $$
Short Answer
Expert verified
The simplified expression is -18.
Step by step solution
01
Understand the Expression
We're given the expression \(-2(27)^{2/3}\). This means we need to first evaluate \(27^{2/3}\) and then multiply the result by \-2\.
02
Evaluate the Fractional Exponent
The expression \(27^{2/3}\) involves a fractional exponent. The base is 27, which can be rewritten as \(3^3\) because \(3 \times 3 \times 3 = 27\). The fractional exponent \({2/3}\) means you raise the expression to the power of 2 and then take the cube root, or vice versa.
03
Simplify the Expression using Cube Root
First, calculate the cube root of 27, which is \((27^{1/3} = 3)\). This is because \(3^3 = 27\).
04
Raise the Result to the Power 2
Now, square the result from the previous step: \(3^2 = 9\). This means \(27^{2/3} = 9\).
05
Apply the Negative Sign and Multiplication
The original expression is \(-2 imes (27)^{2/3}\). Substitute the simplified value \(9\) for \(27^{2/3}\), resulting in \(-2 imes 9 = -18\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Fractional Exponents
Fractional exponents are a way to express powers and roots together. They simplify expressions that involve both operations. For example, the expression \( x^{2/3} \) can be broken down into two steps: raising \( x \) to the power of 2 and then finding the cube root of the result, or performing these steps in the reverse order.
- The numerator of the fractional exponent (here, it is 2) indicates the power to which the number is raised.
- The denominator (in this case, 3) indicates the root to be taken.
Cube Roots
Cube roots are the reverse operation of cubing a number. They answer the question: "What number, multiplied by itself three times, gives me this original number?" Calculating cube roots can reduce numbers to simpler forms, keeping expressions neat.For 27, we know that \( 3^3 = 27 \), so the cube root of 27 is 3, expressed as \( 27^{1/3} = 3 \).When working with cube roots, it's helpful to:
- Understand the cube of basic numbers (like 1, 2, 3, etc.) for quick mental math.
- Use the cube root operation to simplify fractional exponents as shown in this problem.
Negative Numbers
Negative numbers are numbers with a value less than zero. They are crucial for expressing debts, temperatures below freezing, or elevations below sea level. When dealing with expressions, they represent a direction or distance on a number line.For the given exercise, there is a multiplication with a negative number right before the variable. This means:
- Once you simplify \( 27^{2/3} \) to 9, you apply the negative multiplier \(-2\).
- The final result is \(-2 \times 9 = -18\).