Chapter 1: Problem 38
Evaluate each expression without using a calculator. $$ 16^{-3 / 4} $$
Short Answer
Expert verified
The evaluated expression is \( \frac{1}{8} \).
Step by step solution
01
Understanding the Negative Exponent
The expression involves a negative exponent, which means \[ 16^{-3/4} = \frac{1}{16^{3/4}} \]This step involves understanding that a negative exponent indicates taking the reciprocal of the positive exponent.
02
Simplify the Exponent Form
Now, we focus on simplifying \( 16^{3/4} \). The exponent \( 3/4 \) refers to the cube of the fourth root of 16. We can rewrite it as:\[ 16^{3/4} = (16^{1/4})^3 \] where \( 16^{1/4} \) denotes the fourth root of 16.
03
Calculate the Fourth Root
Calculate the fourth root of 16. Since 16 can be written as \( 2^4 \), we have:\[ 16^{1/4} = (2^4)^{1/4} = 2^{4/4} = 2 \]Thus, the fourth root of 16 is 2.
04
Cube the Fourth Root
Now, we cube the result from the previous step:\[ (16^{1/4})^3 = 2^3 = 8 \] This gives us the value of \( 16^{3/4} \) as 8.
05
Take the Reciprocal
Finally, use the result from Step 4 to calculate the reciprocal, which was derived in Step 1:\[ 16^{-3/4} = \frac{1}{8} \]This step concludes the calculations and provides the final answer to the expression.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Negative Exponents
When we encounter a negative exponent, it often looks intimidating, but it's just a different way to express fractions. A negative exponent tells us to take the reciprocal of the base raised to the corresponding positive exponent. For example, when you see \( 16^{-3/4} \), it simply means \( \frac{1}{16^{3/4}} \).
- To deal with negative exponents, remember that the minus sign is there to tell you to "flip" the fraction.
- This "flipping" process is similar whether the exponent is a whole number or a rational number.
Rational Exponents
Rational exponents, such as \( 16^{3/4} \), are another way of expressing roots and powers. The fraction in the exponent \( \frac{3}{4} \) means the fourth root of a number raised to the third power. This can be expressed as \( (16^{1/4})^3 \).
- The denominator in the rational exponent indicates the root. In our example, 4 tells us we're taking the fourth root.
- The numerator indicates the power. Here, 3 means that the fourth root result is to be cubed.
Simplifying Exponents
Simplifying expressions with exponents transforms complex problems into simpler ones. Continuing with \( 16^{3/4} \), we see this simplification is broken down into manageable steps:
- First, you take the fourth root of 16, which means finding a number that, when multiplied by itself four times, gives 16. Knowing that \( 16 = 2^4 \), the fourth root is 2.
- Then, cube this result (that is, multiply it by itself twice more): \( 2^3 = 8 \).
Roots and Powers
Understanding the relationship between roots and powers is key to mastering exponents.
Any number raised to a power is a repeated multiplication, while roots are the opposite: finding what number can be multiplied several times to yield the original number.
In the expression \( 16^{3/4} \):
Any number raised to a power is a repeated multiplication, while roots are the opposite: finding what number can be multiplied several times to yield the original number.
In the expression \( 16^{3/4} \):
- The fourth root: \( 16^{1/4} = 2 \) because \( 2^4 = 16 \).
- The power: \( (2)^3 = 8 \) which completes the calculation.