Chapter 7: Problem 104
f(x)\( and \)g(x)\( are as given. Find \)(f \cdot g)(x) \cdot$ Assume that all variables represent non-negative real numbers. $$ f(x)=\sqrt[4]{2 x}+5 \sqrt{2 x}, g(x)=\sqrt[3]{2 x} $$
Short Answer
Expert verified
(f \cdot g)(x) = (2x)^{7/12} + 5(2x)^{5/6}.
Step by step solution
01
Write down the given functions
The given functions are \[f(x) = \sqrt[4]{2x} + 5\sqrt{2x}\] and \[g(x) = \sqrt[3]{2x}\].
02
Understand the product of functions
We need to find \[(f \cdot g)(x)\], which means multiplying the two functions together: \[f(x) \cdot g(x)\].
03
Substitute the expressions
Substitute the expressions for \[f(x)\] and \[g(x)\] into the product: \[(\sqrt[4]{2x} + 5\sqrt{2x}) \cdot \sqrt[3]{2x}\].
04
Distribute the product
Distribute \[\sqrt[3]{2x}\] to each term in \[\sqrt[4]{2x} + 5\sqrt{2x}\]: \[(\sqrt[4]{2x} \cdot \sqrt[3]{2x}) + (5\sqrt{2x} \cdot \sqrt[3]{2x})\].
05
Simplify each term separately
We'll simplify \[\sqrt[4]{2x} \cdot \sqrt[3]{2x}\] and \[5\sqrt{2x} \cdot \sqrt[3]{2x}\] separately.
06
Simplify the first term
Simplify \[\sqrt[4]{2x} \cdot \sqrt[3]{2x}\]. Use the property of exponents \[a^{m/n} \cdot a^{p/q} = a^{(m/n + p/q)}\]: \[(2x)^{1/4} \cdot (2x)^{1/3} = (2x)^{1/4 + 1/3}\]. Find a common denominator: \[\frac{1}{4} + \frac{1}{3} = \frac{3}{12} + \frac{4}{12} = \frac{7}{12}\]. So, \[(2x)^{7/12}\].
07
Simplify the second term
Simplify \[5\sqrt{2x} \cdot \sqrt[3]{2x}\]: \[5 (2x)^{1/2} \cdot (2x)^{1/3} = 5 (2x)^{1/2 + 1/3}\]. Find a common denominator: \[\frac{1}{2} + \frac{1}{3} = \frac{3}{6} + \frac{2}{6} = \frac{5}{6}\]. So, \[5 (2x)^{5/6}\].
08
Combine the terms
Combine the simplified terms: \[(2x)^{7/12} + 5 (2x)^{5/6}\].
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Multiplication
Function multiplication involves multiplying two functions together to create a new function. In our exercise, we have two functions: \( f(x) = \sqrt[4]{2x} + 5\sqrt{2x} \) and \( g(x) = \sqrt[3]{2x} \). To find \( (f \cdot g)(x) \), we need to multiply these functions: \( f(x) \cdot g(x) \). This means we substitute the expressions given for each function and then multiply them: \( (\sqrt[4]{2x} + 5\sqrt{2x}) \cdot \sqrt[3]{2x} \). Distributing the product, each term in the sum \( \sqrt[4]{2x} + 5\sqrt{2x} \) is multiplied by \( \sqrt[3]{2x} \):\((\sqrt[4]{2x} \cdot \sqrt[3]{2x}) + (5\sqrt{2x} \cdot \sqrt[3]{2x}) \).
Exponent Properties
When working with exponents, knowing the properties can make simplifying expressions easier. One key property is \( a^{m/n} \cdot a^{p/q} = a^{(m/n + p/q)} \). For the term \( \sqrt[4]{2x} \cdot \sqrt[3]{2x} \), we rewrite each radical as an exponent and then add those exponents: \( (2x)^{1/4} \cdot (2x)^{1/3} = (2x)^{1/4 + 1/3} \). Use a common denominator to add \( \frac{1}{4} + \frac{1}{3} = \frac{3}{12} + \frac{4}{12} = \frac{7}{12} \), thus \( (2x)^{7/12} \). For the term \( 5\sqrt{2x} \cdot \sqrt[3]{2x} \), rewrite as \( 5(2x)^{1/2} \cdot (2x)^{1/3} \) and add \( \frac{1}{2} + \frac{1}{3} = \frac{3/6} + \frac{2/6} = \frac{5/6} \), resulting in \( 5(2x)^{5/6} \). Remember these exponent properties are very useful when dealing with radicals.
Radicals
Radicals are expressions that involve roots, such as square roots \( \sqrt{} \), cube roots \( \sqrt[3]{} \), and fourth roots \( \sqrt[4]{} \). To simplify products involving radicals, convert them to rational exponents. For example, \( \sqrt[4]{2x} \) can be written as \( (2x)^{1/4} \). Similarly, \( \sqrt[3]{2x} \) is \( (2x)^{1/3} \). When multiplying these, use the exponent properties discussed earlier. For the problem in the exercise, multiply \( \sqrt[4]{2x} + 5\sqrt{2x} \) with \( \sqrt[3]{2x} \) and simplify each term: \( \sqrt[4]{2x} \cdot \sqrt[3]{2x} \) becomes \( (2x)^{7/12} \) and \( 5\sqrt{2x} \cdot \sqrt[3]{2x} = 5(2x)^{5/6} \). Combining these gives \( (2x)^{7/12} + 5(2x)^{5/6} \). Understanding radicals as exponents helps in simplifying and performing operations on these expressions.