Math  /  Algebra

QuestionGiven f(x)=7xf(x)=7 x and g(x)=7x2+9g(x)=7 x^{2}+9, find the following expressions. (a) (fg)(4)(f \circ g)(4) (b) (gf)(2)(g \circ f)(2) (c) (ff)(1)(f \circ f)(1) (d) (gg)(0)(g \circ g)(0) (a) (fg)(4)=847(f \circ g)(4)=847 \quad (Simplify your answer.) (b) (gf)(2)=(g \circ f)(2)= \square (Simplify your answer.)

Studdy Solution

STEP 1

1. We are given two functions: f(x)=7x f(x) = 7x and g(x)=7x2+9 g(x) = 7x^2 + 9 .
2. We need to find the compositions of these functions for specific values of x x .

STEP 2

1. Calculate (fg)(4)(f \circ g)(4).
2. Calculate (gf)(2)(g \circ f)(2).
3. Calculate (ff)(1)(f \circ f)(1).
4. Calculate (gg)(0)(g \circ g)(0).

STEP 3

Calculate (fg)(4)(f \circ g)(4):
First, find g(4) g(4) :
g(4)=7(4)2+9 g(4) = 7(4)^2 + 9

STEP 4

Simplify g(4) g(4) :
g(4)=7(16)+9 g(4) = 7(16) + 9 g(4)=112+9 g(4) = 112 + 9 g(4)=121 g(4) = 121

STEP 5

Now find f(g(4))=f(121) f(g(4)) = f(121) :
f(121)=7×121 f(121) = 7 \times 121

STEP 6

Simplify f(121) f(121) :
f(121)=847 f(121) = 847

STEP 7

Calculate (gf)(2)(g \circ f)(2):
First, find f(2) f(2) :
f(2)=7×2 f(2) = 7 \times 2

STEP 8

Simplify f(2) f(2) :
f(2)=14 f(2) = 14

STEP 9

Now find g(f(2))=g(14) g(f(2)) = g(14) :
g(14)=7(14)2+9 g(14) = 7(14)^2 + 9

STEP 10

Simplify g(14) g(14) :
g(14)=7(196)+9 g(14) = 7(196) + 9 g(14)=1372+9 g(14) = 1372 + 9 g(14)=1381 g(14) = 1381
The value of (gf)(2)(g \circ f)(2) is:
1381 \boxed{1381}

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