Question

Find (f • g) when f(x) = x^2 + 5x + 6 and g(x) = 1/x+3

Answer 1

Answer:

option D

Step-by-step explanation:

$f(x) = x^2 + 5x + 6$

$g(x)= \frac{1}{x+3}$

(fog)(x) = f(g(x))

Plug in g(x) in f(x)

We plug in 1/x+3 in the place of x  in f(x)

$f(g(x))= f(\frac{1}{x+3})= (\frac{1}{x+3})^2 + 5(\frac{1}{x+3}) + 6$

To simplify it we take LCD

LCD is (x+3)(x+3)

$\frac{1}{(x+3)(x+3)}+5\frac{1*(x+3)}{(x+3)(x+3)}+\frac{6(x+3)(x+3)}{(x+3)(x+3)}$

$\frac{1}{x^2+6x+9}+\frac{(5x+15)}{x^2+6x+9}+\frac{6x^2+36x+54}{x^2+6x+9}$

All the denominators are same so we combine the numerators

$\frac{1+5x+15+6x^2+36x+54}{x^2+6x+9}$

$\frac{6x^2+41x+70}{x^2+6x+9}$

Option D is correct

Answer 2

Answer:

The correct option choice is D. 6x^2 + 41x + 70 / x^2 +6x + 9