Math Problem Statement

Use the given functions to calculate each operation and simplify, if possible. Enter DNE if the operation cannot be computed. f(x) = 1 x + 2

g(x) = 4x − 2

h(x) = −x^2 + 9

j(x) = |x|

(a) (g + h)(3) = (b) (j − f)(−3) = (c) (hg)(−8) = (d)

j f

(4) =

Solution

To solve each part, we will evaluate the functions as required by the operations. Let's go through each part step-by-step.

Given:

  • f(x)=1x+2f(x) = \frac{1}{x + 2}
  • g(x)=4x2g(x) = 4x - 2
  • h(x)=x2+9h(x) = -x^2 + 9
  • j(x)=xj(x) = |x|

(a) (g+h)(3)(g + h)(3)

To find (g+h)(3)(g + h)(3), we calculate g(3)g(3) and h(3)h(3), then add the results.

  1. Calculate g(3)g(3): g(3)=432=122=10g(3) = 4 \cdot 3 - 2 = 12 - 2 = 10

  2. Calculate h(3)h(3): h(3)=(3)2+9=9+9=0h(3) = -(3)^2 + 9 = -9 + 9 = 0

  3. Add g(3)g(3) and h(3)h(3): (g+h)(3)=10+0=10(g + h)(3) = 10 + 0 = 10

So, (g+h)(3)=10(g + h)(3) = 10.

(b) (jf)(3)(j - f)(-3)

To find (jf)(3)(j - f)(-3), we calculate j(3)j(-3) and f(3)f(-3), then subtract f(3)f(-3) from j(3)j(-3).

  1. Calculate j(3)j(-3): j(3)=3=3j(-3) = |-3| = 3

  2. Calculate f(3)f(-3): f(3)=13+2=11=1f(-3) = \frac{1}{-3 + 2} = \frac{1}{-1} = -1

  3. Subtract f(3)f(-3) from j(3)j(-3): (jf)(3)=3(1)=3+1=4(j - f)(-3) = 3 - (-1) = 3 + 1 = 4

So, (jf)(3)=4(j - f)(-3) = 4.

(c) (hg)(8)(hg)(-8)

To find (hg)(8)(hg)(-8), we calculate h(8)h(-8) and g(8)g(-8), then multiply the results.

  1. Calculate h(8)h(-8): h(8)=(8)2+9=64+9=55h(-8) = -(-8)^2 + 9 = -64 + 9 = -55

  2. Calculate g(8)g(-8): g(8)=4(8)2=322=34g(-8) = 4 \cdot (-8) - 2 = -32 - 2 = -34

  3. Multiply h(8)h(-8) and g(8)g(-8): (hg)(8)=(55)(34)=1870(hg)(-8) = (-55) \cdot (-34) = 1870

So, (hg)(8)=1870(hg)(-8) = 1870.

(d) jf(4)\frac{j}{f}(4)

To find jf(4)\frac{j}{f}(4), we calculate j(4)j(4) and f(4)f(4), then divide j(4)j(4) by f(4)f(4).

  1. Calculate j(4)j(4): j(4)=4=4j(4) = |4| = 4

  2. Calculate f(4)f(4): f(4)=14+2=16f(4) = \frac{1}{4 + 2} = \frac{1}{6}

  3. Divide j(4)j(4) by f(4)f(4): jf(4)=416=46=24\frac{j}{f}(4) = \frac{4}{\frac{1}{6}} = 4 \cdot 6 = 24

So, jf(4)=24\frac{j}{f}(4) = 24.

Final Answers:

  • (a) (g+h)(3)=10(g + h)(3) = 10
  • (b) (jf)(3)=4(j - f)(-3) = 4
  • (c) (hg)(8)=1870(hg)(-8) = 1870
  • (d) jf(4)=24\frac{j}{f}(4) = 24

Would you like further details or have any questions?

Related Questions:

  1. How would the solution change if g(x)=4x+2g(x) = 4x + 2 instead of 4x24x - 2?
  2. What would (gf)(3)(g \cdot f)(3) be given these functions?
  3. Can f(x)f(x) ever equal zero? If so, for what value of xx?
  4. How does changing the sign in h(x)=x2+9h(x) = x^2 + 9 affect the answer for (hg)(8)(hg)(-8)?
  5. What would be the result of (j+h)(3)(j + h)(3)?

Tip:

Always verify domain restrictions, particularly with rational functions like f(x)=1x+2f(x) = \frac{1}{x + 2}, to avoid division by zero errors.

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Math Problem Analysis

Mathematical Concepts

Functions
Function Operations
Absolute Value
Rational Functions
Algebra

Formulas

f(x) = 1/(x + 2)
g(x) = 4x − 2
h(x) = −x^2 + 9
j(x) = |x|

Theorems

Function evaluation
Addition of functions
Subtraction of functions
Multiplication of functions
Division of functions

Suitable Grade Level

Grades 9-11