Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
3. Functions
Function Operations
Problem 40
Textbook Question
Find f+g, f−g, fg, and gf. Determine the domain for each function.
f(x)=x, g(x)=x−5
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1
To find \( (f+g)(x) \), add the functions: \( f(x) + g(x) = \sqrt{x} + (x - 5) \). Simplify the expression to get \( \sqrt{x} + x - 5 \). The domain of \( f(x) = \sqrt{x} \) is \( x \geq 0 \), and the domain of \( g(x) = x - 5 \) is all real numbers. Therefore, the domain of \( f+g \) is \( x \geq 0 \).
To find \( (f-g)(x) \), subtract the functions: \( f(x) - g(x) = \sqrt{x} - (x - 5) \). Simplify the expression to get \( \sqrt{x} - x + 5 \). The domain is the same as \( f+g \), which is \( x \geq 0 \).
To find \( (fg)(x) \), multiply the functions: \( f(x) \cdot g(x) = \sqrt{x} \cdot (x - 5) \). This simplifies to \( x\sqrt{x} - 5\sqrt{x} \). The domain is \( x \geq 0 \) because \( \sqrt{x} \) is only defined for non-negative \( x \).
To find \( \left(\frac{f}{g}\right)(x) \), divide the functions: \( \frac{f(x)}{g(x)} = \frac{\sqrt{x}}{x - 5} \). The domain is \( x \geq 0 \) and \( x \neq 5 \) because the denominator cannot be zero.
Summarize the domains: \( f+g \) and \( f-g \) have domain \( x \geq 0 \), \( fg \) has domain \( x \geq 0 \), and \( \frac{f}{g} \) has domain \( x \geq 0 \) and \( x \neq 5 \).
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