Math

QuestionFind and simplify: (a) (fg)(x)(f \circ g)(x), (b) (gf)(x)(g \circ f)(x), (c) (ff)(x)(f \circ f)(x), (d) (gg)(x)(g \circ g)(x), where f(x)=x2+8f(x)=x^{2}+8 and g(x)=x+6g(x)=x+6.

Studdy Solution

STEP 1

Assumptions1. The function f(x)f(x) is given by f(x)=x+8f(x)=x^{}+8 . The function g(x)g(x) is given by g(x)=x+6g(x)=x+6

STEP 2

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

STEP 3

Substitute g(x)=x+6g(x) = x+6 into f(x)=x2+8f(x) = x^{2}+8.
(fg)(x)=(x+6)2+8 (f \circ g)(x) = (x+6)^{2}+8

STEP 4

implify the expression.
(fg)(x)=x2+12x+36+8 (f \circ g)(x) = x^{2} +12x +36 +8

STEP 5

Further simplify the expression.
(fg)(x)=x2+12x+44 (f \circ g)(x) = x^{2} +12x +44

STEP 6

Similarly, to find (gf)(x)(g \circ f)(x), we substitute f(x)f(x) into g(x)g(x).
(gf)(x)=g(f(x)) (g \circ f)(x) = g(f(x))

STEP 7

Substitute f(x)=x2+f(x) = x^{2}+ into g(x)=x+6g(x) = x+6.
(gf)(x)=(x2+)+6 (g \circ f)(x) = (x^{2}+) +6

STEP 8

implify the expression.
(gf)(x)=x2+14 (g \circ f)(x) = x^{2} +14

STEP 9

To find (ff)(x)(f \circ f)(x), we substitute f(x)f(x) into f(x)f(x).
(ff)(x)=f(f(x)) (f \circ f)(x) = f(f(x))

STEP 10

Substitute f(x)=x2+8f(x) = x^{2}+8 into f(x)=x2+8f(x) = x^{2}+8.
(ff)(x)=(x2+8)2+8 (f \circ f)(x) = (x^{2}+8)^{2}+8

STEP 11

Expand and simplify the expression.
(ff)(x)=x4+16x+64+8 (f \circ f)(x) = x^{4} +16x^{} +64 +8

STEP 12

Further simplify the expression.
(ff)(x)=x4+16x2+72 (f \circ f)(x) = x^{4} +16x^{2} +72

STEP 13

To find (gg)(x)(g \circ g)(x), we substitute g(x)g(x) into g(x)g(x).
(gg)(x)=g(g(x)) (g \circ g)(x) = g(g(x))

STEP 14

Substitute g(x)=x+6g(x) = x+6 into g(x)=x+6g(x) = x+6.
(gg)(x)=(x+6)+6 (g \circ g)(x) = (x+6) +6

STEP 15

implify the expression.
(gg)(x)=x+12 (g \circ g)(x) = x +12 So, the solutions are(a) (fg)(x)=x2+12x+44(f \circ g)(x) = x^{2} +12x +44 (b) (gf)(x)=x2+14(g \circ f)(x) = x^{2} +14 (c) (ff)(x)=x4+x2+72(f \circ f)(x) = x^{4} +x^{2} +72 (d) (gg)(x)=x+12(g \circ g)(x) = x +12

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