Chapter 7: Problem 48
For exercises 39-82, simplify. $$ \frac{9 h k}{40 n^{2}} \div \frac{3 h^{2}}{8 n} $$
Short Answer
Expert verified
\(\frac{3k}{5h}\)
Step by step solution
01
- Rewrite the division as multiplication
To simplify \(\frac{9hk}{40n^2} \div \frac{3h^2}{8n}\), rewrite the division as multiplication by the reciprocal. This means \(\frac{9hk}{40n^2} \div \frac{3h^2}{8n}\) becomes \(\frac{9hk}{40n^2} \times \frac{8n}{3h^2}\).
02
- Multiply the fractions
Multiply the numerators together and the denominators together: \(\frac{9hk \times 8n}{40n^2 \times 3h^2} = \frac{72hkn}{120n^2 h^2}\).
03
- Simplify the fraction
To simplify \(\frac{72hkn}{120n^2 h^2}\), start by canceling out common factors in the numerator and the denominator. Here, both 72 and 120 share a common factor of 24. Additionally, cancel out common variables: \(\frac{72hkn}{120n^2 h^2} = \frac{6kn}{10nh} = \frac{3k}{5h}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
algebraic fractions
An algebraic fraction is simply a fraction where the numerator and/or the denominator contain algebraic expressions instead of just numbers. Think of it just like a regular fraction but with variables and constants mixed in. For example, in the exercise given: \( \frac{9hk}{40n^2} \), the numerator \(9hk\) and the denominator \(40n^2\) are both algebraic expressions.
To work with algebraic fractions, you often need to follow the same basic rules that you use with numerical fractions:
To work with algebraic fractions, you often need to follow the same basic rules that you use with numerical fractions:
- Adding or subtracting requires a common denominator
- Multiplication is done across numerators and denominators
- Division involves multiplying by the reciprocal
multiplication of fractions
Multiplying fractions, whether they're numerical or algebraic, follows a straightforward rule: multiply the numerators together and the denominators together. In our given problem, after rewriting the division as multiplication, we got: \( \frac{9hk}{40n^2} \times \frac{8n}{3h^2} \).
This means we multiply the numerators (\(9hk \times 8n\)) and the denominators (\(40n^2 \times 3h^2\)). To do the math:
This gives us \( \frac{72hkn}{120n^2 h^2} \). It looks more complex now, but don't worry, we can simplify it next!
This means we multiply the numerators (\(9hk \times 8n\)) and the denominators (\(40n^2 \times 3h^2\)). To do the math:
- Numerators: \(9hk \times 8n = 72hkn\)
- Denominators: \(40n^2 \times 3h^2 = 120n^2 h^2\)
This gives us \( \frac{72hkn}{120n^2 h^2} \). It looks more complex now, but don't worry, we can simplify it next!
simplifying fractions
Simplifying algebraic fractions follows the same principle as simplifying numerical fractions: find common factors in the numerator and the denominator and cancel them out. For our fraction \(\frac{72hkn}{120n^2 h^2}\):
Breaking it down step-by-step, we get:
1. Cancel numerical common factors: \(\frac{72}{120} = \frac{6}{10}\).
2. Simplify variables: \(\frac{6hk n}{10n^2 h^2} = \frac{6k}{10nh} = \frac{3k}{5h}\).
And that's our simplified fraction: \( \frac{3k}{5h} \)!
- Notice both 72 and 120 share a common factor of 24. Think of it like reducing a fraction like 24/48 to 1/2.
- The variables can also be simplified by canceling out common factors. For example, \(h\) in the numerator and \(h^2\) in the denominator can be simplified to remove one \(h\).
Breaking it down step-by-step, we get:
1. Cancel numerical common factors: \(\frac{72}{120} = \frac{6}{10}\).
2. Simplify variables: \(\frac{6hk n}{10n^2 h^2} = \frac{6k}{10nh} = \frac{3k}{5h}\).
And that's our simplified fraction: \( \frac{3k}{5h} \)!
reciprocal
A reciprocal is what you get when you flip a fraction upside down. For example, the reciprocal of \( \frac{a}{b} \) is \( \frac{b}{a} \).
When dealing with dividing fractions, you multiply by the reciprocal of the divisor. In our problem, we started with:
Thus, we effectively turned the division problem into a multiplication one. Multiplying by the reciprocal simplifies the fraction and makes solving the problem much easier. Make sure to always double-check the reciprocal to avoid errors!
When dealing with dividing fractions, you multiply by the reciprocal of the divisor. In our problem, we started with:
- \( \frac{9hk}{40n^2} \times \frac{8n}{3h^2} \)
- The reciprocal of \( \frac{3h^2}{8n} \) is \( \frac{8n}{3h^2} \)
Thus, we effectively turned the division problem into a multiplication one. Multiplying by the reciprocal simplifies the fraction and makes solving the problem much easier. Make sure to always double-check the reciprocal to avoid errors!