Math Problem Statement

Tentukan nilai berikut, jika f(x) = x 3 + 1 dan g(x) = 1 x untuk (a) (f + g)(x) (b) (f − g)(2x) (c) (f ◦ g)(x) (d) (g ◦ f)(x) (e) ((f − g) ◦ g)(x)

Solution

Given the functions f(x)=x3+1f(x) = x^3 + 1 and g(x)=1xg(x) = \frac{1}{x}, let's calculate the values for each of the specified operations:

(a) (f+g)(x)(f + g)(x)

(f+g)(x)=f(x)+g(x)(f + g)(x) = f(x) + g(x)

=(x3+1)+1x= (x^3 + 1) + \frac{1}{x}

=x3+1+1x= x^3 + 1 + \frac{1}{x}

(b) (fg)(2x)(f - g)(2x)

First, find f(2x)f(2x) and g(2x)g(2x):

f(2x)=(2x)3+1=8x3+1f(2x) = (2x)^3 + 1 = 8x^3 + 1

g(2x)=12xg(2x) = \frac{1}{2x}

Now, calculate (fg)(2x)(f - g)(2x):

(fg)(2x)=f(2x)g(2x)=(8x3+1)12x(f - g)(2x) = f(2x) - g(2x) = (8x^3 + 1) - \frac{1}{2x}

=8x3+112x= 8x^3 + 1 - \frac{1}{2x}

(c) (fg)(x)(f \circ g)(x)

(fg)(x)=f(g(x))(f \circ g)(x) = f(g(x)):

f(g(x))=f(1x)=(1x)3+1f(g(x)) = f\left(\frac{1}{x}\right) = \left(\frac{1}{x}\right)^3 + 1

=1x3+1= \frac{1}{x^3} + 1

(d) (gf)(x)(g \circ f)(x)

(gf)(x)=g(f(x))(g \circ f)(x) = g(f(x)):

g(f(x))=g(x3+1)=1x3+1g(f(x)) = g(x^3 + 1) = \frac{1}{x^3 + 1}

(e) ((fg)g)(x)((f - g) \circ g)(x)

((fg)g)(x)=(fg)(g(x))((f - g) \circ g)(x) = (f - g)(g(x)):

  1. Find f(g(x))f(g(x)) and g(g(x))g(g(x)):

f(g(x))=f(1x)=1x3+1f(g(x)) = f\left(\frac{1}{x}\right) = \frac{1}{x^3} + 1

g(g(x))=g(1x)=xg(g(x)) = g\left(\frac{1}{x}\right) = x

  1. Now calculate:

(fg)(g(x))=f(g(x))g(g(x))(f - g)(g(x)) = f(g(x)) - g(g(x))

=(1x3+1)x= \left(\frac{1}{x^3} + 1\right) - x

=1x3+1x= \frac{1}{x^3} + 1 - x

Would you like more details or have any questions?

Here are some related questions to expand on this topic:

  1. How do you find the domain of a composite function?
  2. What happens to the range of a function when it's composed with another function?
  3. How can you determine if a composite function is invertible? 4

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Math Problem Analysis

Mathematical Concepts

Algebra
Functions
Composite Functions
Operations on Functions

Formulas

(f + g)(x) = f(x) + g(x)
(f - g)(x) = f(x) - g(x)
(f ◦ g)(x) = f(g(x))
(g ◦ f)(x) = g(f(x))
f(x) = x^3 + 1
g(x) = 1/x

Theorems

Composition of Functions
Function Addition and Subtraction

Suitable Grade Level

Grades 10-12