Problem 7
Question
Find all the real cube roots of each number. $$ -\frac{27}{216} $$
Step-by-Step Solution
Verified Answer
The real cube root of \( -\frac{27}{216} \) is \( -\frac{1}{2} \).
1Step 1 - Simplify the Fraction
Firstly, simplify the fraction by dividing both the numerator and the denominator by their greatest common divisor, which is 27.
2Step 2 - Simplifying Further
Once the fraction is simplified to \( -\frac{1}{8} \) we identify that the cube root of -1 is -1 and the cube root of 8 is 2.
3Step 3 - Find the Cube Root
We now find the cube root of the simplified fraction by taking the cube root of the numerator and the cube root of the denominator separately. The cube root of -1 is -1 and the cube root of 8 is 2. Therefore, the cube root of \( -\frac{1}{8} \) is \( -\frac{1}{2} \).
Key Concepts
Simplifying FractionsCube Root CalculationReal Numbers
Simplifying Fractions
Understanding how to simplify fractions is crucial, as it can make calculations easier and help us to better find the value of mathematical expressions. To simplify a fraction, we search for the greatest common divisor (GCD) of the numerator and the denominator. The GCD is the largest number that divides both without leaving a remainder.
For instance, in the exercise given, we start off with the fraction \( -\frac{27}{216} \) where 27 is our best candidate for the GCD since it divides both the numerator and the denominator. After simplifying with this GCD, we're left with \( -\frac{1}{8} \), a much simpler form that is easier to work with. If we encounter larger numbers, we may use prime factorization or other techniques to find the GCD. Remember, a simpler fraction often leads to a clearer path to the solution.
For instance, in the exercise given, we start off with the fraction \( -\frac{27}{216} \) where 27 is our best candidate for the GCD since it divides both the numerator and the denominator. After simplifying with this GCD, we're left with \( -\frac{1}{8} \), a much simpler form that is easier to work with. If we encounter larger numbers, we may use prime factorization or other techniques to find the GCD. Remember, a simpler fraction often leads to a clearer path to the solution.
Cube Root Calculation
The cube root of a number \( x \) is a value that, when multiplied by itself three times (cubed), gives the original number \( x \). In mathematical terms, if \( a^3 = x \), then \( a \) is the cube root of \( x \).
In our particular exercise, we are working with a negative fraction. It's important to note that real cube roots can be negative since cubing a negative number results in another negative. We start by calculating the cube root of the simplified fraction \( -\frac{1}{8} \). We find the cube root of \( -1 \) and \( 8 \) separately, giving us \( -1 \) and \( 2 \) respectively. Therefore, the cube root of \( -\frac{1}{8} \) is \( -\frac{1}{2} \) as cube roots are distributed over the fraction. Cube root calculation can often be simplified by breaking down the problem into smaller parts.
In our particular exercise, we are working with a negative fraction. It's important to note that real cube roots can be negative since cubing a negative number results in another negative. We start by calculating the cube root of the simplified fraction \( -\frac{1}{8} \). We find the cube root of \( -1 \) and \( 8 \) separately, giving us \( -1 \) and \( 2 \) respectively. Therefore, the cube root of \( -\frac{1}{8} \) is \( -\frac{1}{2} \) as cube roots are distributed over the fraction. Cube root calculation can often be simplified by breaking down the problem into smaller parts.
Real Numbers
Real numbers are the set of numbers that include both rational and irrational numbers, encompassing every number that can be found on the number line. This includes both positive and negative numbers, as well as zero.
In the context of cube roots, every real number has one real cube root. This differs from square roots where negative numbers do not have real square roots since squaring any real number always results in a positive number or zero. However, with cube roots, because the power is odd, negative numbers remain negative, allowing for negative cube roots to exist with real numbers, just as we saw in our exercise with \( -\frac{27}{216} \) which simplified to \( -\frac{1}{8} \) and had a real cube root of \( -\frac{1}{2} \). Understanding the properties of real numbers can guide us when dealing with roots and exponents, ensuring that we arrive at the correct solution within the realm of real numbers.
In the context of cube roots, every real number has one real cube root. This differs from square roots where negative numbers do not have real square roots since squaring any real number always results in a positive number or zero. However, with cube roots, because the power is odd, negative numbers remain negative, allowing for negative cube roots to exist with real numbers, just as we saw in our exercise with \( -\frac{27}{216} \) which simplified to \( -\frac{1}{8} \) and had a real cube root of \( -\frac{1}{2} \). Understanding the properties of real numbers can guide us when dealing with roots and exponents, ensuring that we arrive at the correct solution within the realm of real numbers.
Other exercises in this chapter
Problem 7
Multiply, if possible. Then simplify. $$ \sqrt[3]{9} \cdot \sqrt[3]{-24} $$
View solution Problem 7
Simplify each expression. $$2^{\frac{1}{2}} \cdot 32^{\frac{1}{2}}$$
View solution Problem 8
Graph each function. \(y=\sqrt{x-4}\)
View solution Problem 8
Find the inverse of each function. Is the inverse a function? $$ y=5-2 x^{2} $$
View solution