Math  /  Algebra

QuestionQuestion 10 (1 point) Find gfg \circ f and the domain of the composite function. f(x)=x2+4,g(x)=xf(x)=x^{2}+4, g(x)=\sqrt{x} a (x4)4\sqrt{(x-4)^{4}} Domain of gfg \circ f : all real numbers xx b (x4)4(x-4)^{4} Domain of gfg \circ f : all real numbers xx c x2+4\sqrt{x^{2}+4} Domain of gfg \circ f : all real numbers xx d (x+4)4\quad(x+4)^{4} Domain of gfg \circ f : all real numbers xx e (x+4)4\sqrt{(x+4)^{4}} Domain of gfg \circ f : all real numbers xx

Studdy Solution

STEP 1

1. The composite function gf g \circ f is defined as g(f(x)) g(f(x)) .
2. The domain of a composite function gf g \circ f consists of all x x such that f(x) f(x) is in the domain of g g .

STEP 2

1. Determine the expression for gf g \circ f .
2. Determine the domain of gf g \circ f .

STEP 3

First, find the expression for gf g \circ f . This means substituting f(x) f(x) into g(x) g(x) :
Given: f(x)=x2+4 f(x) = x^2 + 4 g(x)=x g(x) = \sqrt{x}
The composite function gf g \circ f is: g(f(x))=g(x2+4)=x2+4 g(f(x)) = g(x^2 + 4) = \sqrt{x^2 + 4}

STEP 4

Determine the domain of gf g \circ f .
The function g(x)=x g(x) = \sqrt{x} is defined for x0 x \geq 0 . Therefore, f(x) f(x) must satisfy: x2+40 x^2 + 4 \geq 0
Since x2+4 x^2 + 4 is always positive for all real numbers x x (as x20 x^2 \geq 0 and adding 4 makes it strictly positive), the domain of gf g \circ f is all real numbers.
The correct answer is: c x2+4\sqrt{x^{2}+4} with Domain of gf g \circ f : all real numbers x x .

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