Math

QuestionEvaluate (fg)(x)(f \circ g)(x) and find its domain. Given f(x)=5x2+36f(x)=\frac{5}{x^{2}+36} and g(x)=4+xg(x)=\sqrt{4+x}.

Studdy Solution

STEP 1

Assumptions1. The function f(x)f(x) is given by f(x)=5x+36f(x)=\frac{5}{x^{}+36} . The function g(x)g(x) is given by g(x)=4+xg(x)=\sqrt{4+x}
3. We need to evaluate the composite function (fg)(x)(f \circ g)(x) and find its domain in interval notation.

STEP 2

First, let's evaluate the composite function (fg)(x)(f \circ g)(x). The composite function (fg)(x)(f \circ g)(x) is defined as f(g(x))f(g(x)).
(fg)(x)=f(g(x))(f \circ g)(x)=f(g(x))

STEP 3

Now, plug in the given function g(x)g(x) into the function f(x)f(x).
(fg)(x)=f(+x)(f \circ g)(x)=f(\sqrt{+x})

STEP 4

Substitute g(x)g(x) into f(x)f(x).
(fg)(x)=(4+x)2+36(f \circ g)(x)=\frac{}{(\sqrt{4+x})^{2}+36}

STEP 5

implify the expression.
(fg)(x)=54+x+36(f \circ g)(x)=\frac{5}{4+x+36}

STEP 6

Further simplify the expression.
(fg)(x)=540+x(f \circ g)(x)=\frac{5}{40+x}

STEP 7

Now, let's find the domain of the composite function (fg)(x)(f \circ g)(x). The domain of a function is the set of all possible input values (x-values) which will produce a valid output.
The denominator of the function (fg)(x)(f \circ g)(x) cannot be zero, as division by zero is undefined. Therefore, we need to find the x-values for which the denominator is not zero.
40+x040+x \neq0

STEP 8

olve the inequality to find the x-values that satisfy the condition.
x40x \neq -40

STEP 9

The domain of the function (fg)(x)(f \circ g)(x) is all real numbers except 40-40. In interval notation, this is written as (,40)(40,)(-\infty, -40) \cup (-40, \infty).
So, the composite function (fg)(x)(f \circ g)(x) is 540+x\frac{5}{40+x} and its domain in interval notation is (,40)(40,)(-\infty, -40) \cup (-40, \infty).

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