Questions: The functions f and g are defined as f(x)=x-5, g(x)=√(x+6).
a) Find the domain of f, g, f+g, f-g, fg, ff, f/g, and g/f.
b) Find (f+g)(x), (f-g)(x), (fg)(x), (f)(x),(f/g)(x), and (g/f)(x).
a) The domain of f is (-∞, ∞).
(Type your answer in interval notation.)
The domain of g is .
(Type your answer in interval notation.)
Transcript text: The functions $f$ and $g$ are defined as $f(x)=x-5, g(x)=\sqrt{x+6}$.
a) Find the domain of $f, g, f+g, f-g, f g, f f, \frac{f}{g}$, and $\frac{g}{f}$.
b) Find $(f+g)(x)$, $(f-g)(x)$, $(f g)(x)$, $(f)(x),\left(\frac{f}{g}\right)(x)$, and $\left(\frac{g}{f}\right)(x)$.
a) The domain of $f$ is $(-\infty, \infty)$.
(Type your answer in interval notation.)
The domain of $g$ is $\square$ .
(Type your answer in interval notation.)
Solution
Solution Steps
To solve the given problem, we need to determine the domains of the functions f and g, as well as their combinations. Then, we will find the expressions for the combined functions.
Part (a)
Domain of f(x)=x−5: Since f(x) is a linear function, its domain is all real numbers, (−∞,∞).
Domain of g(x)=x+6: The expression inside the square root must be non-negative, so x+6≥0. Therefore, the domain is [−6,∞).
For the combined functions:
f+g: The domain is the intersection of the domains of f and g, which is [−6,∞).
f−g: The domain is the same as f+g, which is [−6,∞).
f⋅g: The domain is the same as f+g, which is [−6,∞).
gf: The domain is [−6,∞) excluding points where g(x)=0. Since g(x)=x+6, g(x)=0 when x=−6. Thus, the domain is (−6,∞).
fg: The domain is [−6,∞) excluding points where f(x)=0. Since f(x)=x−5, f(x)=0 when x=5. Thus, the domain is [−6,5)∪(5,∞).
Part (b)
(f+g)(x): This is f(x)+g(x).
(f−g)(x): This is f(x)−g(x).
(f⋅g)(x): This is f(x)⋅g(x).
(gf)(x): This is g(x)f(x).
(fg)(x): This is f(x)g(x).
Step 1: Determine the Domain of f(x)
The function f(x)=x−5 is a linear function. Linear functions are defined for all real numbers.
Domain of f:(−∞,∞)
Step 2: Determine the Domain of g(x)
The function g(x)=x+6 is defined when the expression inside the square root is non-negative.
x+6≥0⟹x≥−6
Domain of g:[−6,∞)
Step 3: Determine the Domain of Combined Functions
f+g: The domain is the intersection of the domains of f and g.
Domain of f+g:[−6,∞)
f−g: The domain is the same as f+g.
Domain of f−g:[−6,∞)
f⋅g: The domain is the same as f+g.
Domain of f⋅g:[−6,∞)
gf: The domain is [−6,∞) excluding points where g(x)=0. Since g(x)=x+6, g(x)=0 when x=−6.
Domain of gf:(−6,∞)
fg: The domain is [−6,∞) excluding points where f(x)=0. Since f(x)=x−5, f(x)=0 when x=5.
Domain of fg:[−6,5)∪(5,∞)
Step 4: Find the Expressions for Combined Functions