Question

For the given functions f and g, complete parts (a)-(h). For parts (a)-(d), also find the domain. f(x) = 4x+9; g(x)=9x - 5​

Answer 1

Explanation:

(a) Find f(g(x)).

To find f(g(x)), we first need to find g(x) and then substitute it into f(x).

g(x) = 9x - 5

f(g(x)) = f(9x - 5) = 4(9x - 5) + 9 = 36x - 11

Therefore, f(g(x)) = 36x - 11.

(b) Find g(f(x)).

To find g(f(x)), we first need to find f(x) and then substitute it into g(x).

f(x) = 4x + 9

g(f(x)) = g(4x + 9) = 9(4x + 9) - 5 = 36x + 76

Therefore, g(f(x)) = 36x + 76.

(c) Find f(f(x)).

To find f(f(x)), we need to substitute f(x) into f(x).

f(f(x)) = 4(4x + 9) + 9 = 16x + 45

Therefore, f(f(x)) = 16x + 45.

(d) Find g(g(x)).

To find g(g(x)), we need to substitute g(x) into g(x).

g(g(x)) = 9(9x - 5) - 5 = 81x - 50

Therefore, g(g(x)) = 81x - 50.

Domain of f(x) and g(x): Since both f(x) and g(x) are linear functions, their domains are all real numbers.

(e) Find the inverse of f(x).

To find the inverse of f(x), we need to switch the roles of x and f(x) and solve for f(x).

y = 4x + 9

x = 4y + 9

x - 9 = 4y

y = (x - 9) / 4

Therefore, the inverse of f(x) is f^(-1)(x) = (x - 9) / 4.

(f) Find the inverse of g(x).

To find the inverse of g(x), we need to switch the roles of x and g(x) and solve for g(x).

y = 9x - 5

x = 9y - 5

x + 5 = 9y

y = (x + 5) / 9

Therefore, the inverse of g(x) is g^(-1)(x) = (x + 5) / 9.

(g) Find the domain of f^(-1)(x).

The domain of f^(-1)(x) is the range of f(x). Since f(x) is a linear function, its range is all real numbers. Therefore, the domain of f^(-1)(x) is also all real numbers.

(h) Find the domain of g^(-1)(x).

The domain of g^(-1)(x) is the range of g(x). Since g(x) is a linear function, its range is all real numbers. Therefore, the domain of g^(-1)(x) is also all real numbers.

Answer 2

(a) Find (f + g)(x)

To find (f + g)(x), we add the two functions f(x) and g(x):

(f + g)(x) = f(x) + g(x) = (4x + 9) + (9x - 5) = 13x + 4

The domain of (f + g)(x) is all real numbers, since there are no restrictions on x that would make (f + g)(x) undefined.

(b) Find (f - g)(x)

To find (f - g)(x), we subtract the function g(x) from f(x):

(f - g)(x) = f(x) - g(x) = (4x + 9) - (9x - 5) = -5x + 14

The domain of (f - g)(x) is all real numbers, since there are no restrictions on x that would make (f - g)(x) undefined.

(c) Find (f * g)(x)

To find (f * g)(x), we multiply the two functions f(x) and g(x):

(f * g)(x) = f(x) * g(x) = (4x + 9)(9x - 5) = 36x^2 + 11x - 45

The domain of (f * g)(x) is all real numbers, since there are no restrictions on x that would make (f * g)(x) undefined.

(d) Find (f / g)(x)

To find (f / g)(x), we divide the function f(x) by g(x):

(f / g)(x) = f(x) / g(x) = (4x + 9) / (9x - 5)

The domain of (f / g)(x) is all real numbers except x = 5/9, since this value would make the denominator of (f / g)(x) equal to zero, resulting in division by zero, which is undefined.

(e) Find f(g(x))

To find f(g(x)), we substitute g(x) into the expression for f(x):

f(g(x)) = 4g(x) + 9

Substituting the expression for g(x), we get:

f(g(x)) = 4(9x - 5) + 9 = 36x - 11

The domain of f(g(x)) is all real numbers, since there are no restrictions on x that would make f(g(x)) undefined.

(f) Find g(f(x))

To find g(f(x)), we substitute f(x) into the expression for g(x):

g(f(x)) = 9f(x) - 5

Substituting the expression for f(x), we get:

g(f(x)) = 9(4x + 9) - 5 = 36x + 76

The domain of g(f(x)) is all real numbers, since there are no restrictions on x that would make g(f(x)) undefined.

(g) Find f(f(x))

To find f(f(x)), we substitute f(x) into the expression for f(x):

f(f(x)) = 4f(x) + 9

Substituting the expression for f(x), we get:

f(f(x)) = 4(4x + 9) + 9 = 16x + 45

The domain of f(f(x)) is all real numbers, since there are no restrictions on x that would make f(f(x)) undefined.

(h) Find g(g(x))

To find g(g(x)), we substitute g(x) into the expression for g(x):

g(g(x)) = 9

Explanation: