Math  /  Algebra

QuestionFor f(x)=xf(x)=\sqrt{x} and g(x)=6x+1g(x)=6 x+1, find the following composite functions and state the domain of each. (a) fgf \circ g (b) gfg \circ f (c) fff \circ f (d) ggg \circ g

Studdy Solution

STEP 1

1. We are given two functions: f(x)=x f(x) = \sqrt{x} and g(x)=6x+1 g(x) = 6x + 1 .
2. We need to find the composite functions fg f \circ g , gf g \circ f , ff f \circ f , and gg g \circ g .
3. We need to determine the domain of each composite function.

STEP 2

1. Find the composite function fg f \circ g and its domain.
2. Find the composite function gf g \circ f and its domain.
3. Find the composite function ff f \circ f and its domain.
4. Find the composite function gg g \circ g and its domain.

STEP 3

Find the composite function fg f \circ g :
(fg)(x)=f(g(x))=f(6x+1)=6x+1 (f \circ g)(x) = f(g(x)) = f(6x + 1) = \sqrt{6x + 1}

STEP 4

Determine the domain of fg f \circ g :
The expression inside the square root, 6x+1 6x + 1 , must be non-negative:
6x+10 6x + 1 \geq 0 6x1 6x \geq -1 x16 x \geq -\frac{1}{6}
Thus, the domain of fg f \circ g is x16 x \geq -\frac{1}{6} .

STEP 5

Find the composite function gf g \circ f :
(gf)(x)=g(f(x))=g(x)=6x+1 (g \circ f)(x) = g(f(x)) = g(\sqrt{x}) = 6\sqrt{x} + 1

STEP 6

Determine the domain of gf g \circ f :
The expression inside the square root, x x , must be non-negative:
x0 x \geq 0
Thus, the domain of gf g \circ f is x0 x \geq 0 .

STEP 7

Find the composite function ff f \circ f :
(ff)(x)=f(f(x))=f(x)=x=x1/4 (f \circ f)(x) = f(f(x)) = f(\sqrt{x}) = \sqrt{\sqrt{x}} = x^{1/4}

STEP 8

Determine the domain of ff f \circ f :
The expression inside the square root, x x , must be non-negative:
x0 x \geq 0
Thus, the domain of ff f \circ f is x0 x \geq 0 .

STEP 9

Find the composite function gg g \circ g :
(gg)(x)=g(g(x))=g(6x+1)=6(6x+1)+1=36x+6+1=36x+7 (g \circ g)(x) = g(g(x)) = g(6x + 1) = 6(6x + 1) + 1 = 36x + 6 + 1 = 36x + 7

STEP 10

Determine the domain of gg g \circ g :
Since gg g \circ g is a linear function, its domain is all real numbers.
The composite functions and their domains are: (a) fg(x)=6x+1 f \circ g(x) = \sqrt{6x + 1} , domain: x16 x \geq -\frac{1}{6} (b) gf(x)=6x+1 g \circ f(x) = 6\sqrt{x} + 1 , domain: x0 x \geq 0 (c) ff(x)=x1/4 f \circ f(x) = x^{1/4} , domain: x0 x \geq 0 (d) gg(x)=36x+7 g \circ g(x) = 36x + 7 , domain: all real numbers

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