Math  /  Algebra

QuestionFind (fg)(x)(f \circ g)(x) and (gf)(x)(g \circ f)(x) and the domain of each. f(x)=x+17,g(x)=x17f(x)=x+17, g(x)=x-17 (fg)(x)=(f \circ g)(x)= \square (Simplify your answer.)

Studdy Solution

STEP 1

1. We are given two functions: f(x)=x+17 f(x) = x + 17 and g(x)=x17 g(x) = x - 17 .
2. We need to find the compositions (fg)(x) (f \circ g)(x) and (gf)(x) (g \circ f)(x) .
3. The domain of a composition of functions is the set of all x x such that the composition is defined.

STEP 2

1. Find the composition (fg)(x) (f \circ g)(x) .
2. Simplify (fg)(x) (f \circ g)(x) .
3. Find the domain of (fg)(x) (f \circ g)(x) .
4. Find the composition (gf)(x) (g \circ f)(x) .
5. Simplify (gf)(x) (g \circ f)(x) .
6. Find the domain of (gf)(x) (g \circ f)(x) .

STEP 3

To find (fg)(x) (f \circ g)(x) , we substitute g(x) g(x) into f(x) f(x) . This means we replace every x x in f(x) f(x) with g(x) g(x) .
(fg)(x)=f(g(x))=f(x17) (f \circ g)(x) = f(g(x)) = f(x - 17)

STEP 4

Now, simplify f(x17) f(x - 17) using the definition of f(x) f(x) .
f(x17)=(x17)+17 f(x - 17) = (x - 17) + 17
Simplify the expression:
(x17)+17=x (x - 17) + 17 = x
Thus, (fg)(x)=x (f \circ g)(x) = x .

STEP 5

The domain of (fg)(x)=x (f \circ g)(x) = x is the set of all real numbers because there are no restrictions on x x .

STEP 6

To find (gf)(x) (g \circ f)(x) , we substitute f(x) f(x) into g(x) g(x) . This means we replace every x x in g(x) g(x) with f(x) f(x) .
(gf)(x)=g(f(x))=g(x+17) (g \circ f)(x) = g(f(x)) = g(x + 17)

STEP 7

Now, simplify g(x+17) g(x + 17) using the definition of g(x) g(x) .
g(x+17)=(x+17)17 g(x + 17) = (x + 17) - 17
Simplify the expression:
(x+17)17=x (x + 17) - 17 = x
Thus, (gf)(x)=x (g \circ f)(x) = x .

STEP 8

The domain of (gf)(x)=x (g \circ f)(x) = x is the set of all real numbers because there are no restrictions on x x .
The compositions are: (fg)(x)=x (f \circ g)(x) = x (gf)(x)=x (g \circ f)(x) = x
The domain of each composition is all real numbers.

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