Math

QuestionFind (fg)(x)(f \circ g)(x) for f(x)=xx+9f(x)=\frac{x}{x+9} and g(x)=8x21g(x)=\frac{8}{x^{2}-1}; state the domain in interval notation.

Studdy Solution

STEP 1

Assumptions1. The function f(x)f(x) is given by f(x)=xx+9f(x)=\frac{x}{x+9} . The function g(x)g(x) is given by g(x)=8x1g(x)=\frac{8}{x^{}-1}
3. We are asked to find the composition of the functions, denoted as (fg)(x)(f \circ g)(x)

STEP 2

The composition of two functions, ff and gg, denoted as (fg)(x)(f \circ g)(x), is defined as f(g(x))f(g(x)). This means that we substitute g(x)g(x) into the function f(x)f(x).

STEP 3

Substitute g(x)g(x) into f(x)f(x) to find (fg)(x)(f \circ g)(x).
(fg)(x)=f(g(x))=f(8x21)(f \circ g)(x) = f(g(x)) = f\left(\frac{8}{x^{2}-1}\right)

STEP 4

Now, replace xx in f(x)f(x) with g(x)g(x).
(fg)(x)=8x218x21+9(f \circ g)(x) = \frac{\frac{8}{x^{2}-1}}{\frac{8}{x^{2}-1} +9}

STEP 5

implify the expression by finding a common denominator for the fractions in the numerator and the denominator.
(fg)(x)=8x218+9x29x21(f \circ g)(x) = \frac{\frac{8}{x^{2}-1}}{\frac{8+9x^{2}-9}{x^{2}-1}}

STEP 6

implify the expression further by multiplying the numerator and the denominator by (x21)(x^{2}-1) to get rid of the complex fraction.
(fg)(x)=88+9x29(f \circ g)(x) = \frac{8}{8+9x^{2}-9}

STEP 7

implify the denominator.
(fg)(x)=9x21(f \circ g)(x) = \frac{}{9x^{2}-1}This is the composition of the functions ff and gg.

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