Problem Statement

(6,8)
(2,4)
-8*4

Calculate the composite functions f º g and g º f, and determine their domains.

 
Step 1

To calculate (f º g)(x) = f(g(x)), substitue into the expression for f(x) and simplify the expression to a single fraction.

Question Sequence

Question 1

(f º g)(x) = f(g(x))

, where a =

Incorrect
Correct

 
Step 2

Similarly, calculate (g º f)(x) = g(f(x)) by substituting into the expression for g(x) and simplify the expression.

Question Sequence

Question 2

(g º f)(x) = g(f(x))

, where b =

Incorrect
Correct

 
Step 3

To obtain the domain of either f º g or g º f, we need to find the domain of f(x) and g(x) individually.

Since f(x) and g(x) are both rational functions, the only x-values that need to be excluded are those that make the denominator zero.

For f(x), the denominator is x8 + 1 and is never zero.

Question Sequence

Question 3

Thus the domain of f(x) is

A.
B.
C.
D.
E.
F.

2
Correct.
Incorrect.

 
Step 4

Since (f º g)(x) = f(g(x)), f(x) takes as inputs the values from g(x) to obtain the domain for
(f º g)(x), we need to intersect the domain of g(x) with the domain of the expression for
(f º g)(x).

Now (f º g)(x) = is a rational function so that the only x-values that need to be excluded are those that make the denominator zero or undefined. The denominator of (f º g)(x) is x-32+1, which is never zero.

Question 6

Thus the domain of (f º g)(x)= is

A.
B.
C.
D.
E.
F.

Correct.
Incorrect.

 
Step 5

Since (g º f)(x) = g(f(x)), g(x) takes, as inputs, the values from f(x), to find the domain for
(g º f)(x) we need to intersect the domain of f(x) with the domain of the expression for
(g º f)(x).

Now (g º f)(x) = (x8 + 1)4 is a polynomial function, which is defined for all real numbers.

Question Sequence

Question 7

Thus the domain of (g º f)(x) = (x8 + 1)4 is

A.
B.
C.
D.
E.
F.

Correct.
Incorrect.