Question

Help with 8 and 9??? Please help me out! Correct answers please

Answer 1

Answer:

  8.  (-∞, 0) ∪ (0, 1/3) ∪ (1/3, ∞)

  9.  f(g(x)) = 4x/(1+6x)

Step-by-step explanation:

8. For f(g(x)) to be defined, g(x) must be defined and f(g(x)) must be defined.

g(x) will be defined for all x≠0. f(g(x)) will be defined for g(x)≠4. Solving g(x)=4, we find the value of x is 1/3. (The answer choices give a clue.)

So, the domain of f(g(x)) is all x that is not 0 or 1/3. Only one answer choice makes those particular exclusions:

  (-∞, 0) ∪ (0, 1/3) ∪ (1/3, ∞)

__

9. Substituting the definition of g(x) into the expression for f(x), we get ...

$\displaystyle (f\circ g)(x)=f(g(x))=\frac{2}{g(x)+3}=\frac{2}{\frac{1}{2x}+3}\\\\=\frac{2}{\left(\frac{1+6x}{2x}\right)}\\\\(f\circ g)(x)=\frac{4x}{1+6x}$