F of x equals 2x squared- x - 6

G of x equals x squared + 3x - 10
What is f over g of X then find the domain of f over g of x

1 answer

To find \( \frac{f(x)}{g(x)} \), we first need to define \( f(x) \) and \( g(x) \).

Given: \[ f(x) = 2x^2 - x - 6 \] \[ g(x) = x^2 + 3x - 10 \]

Now, we can calculate \( \frac{f(x)}{g(x)} \): \[ \frac{f(x)}{g(x)} = \frac{2x^2 - x - 6}{x^2 + 3x - 10} \]

Next, let's factor both the numerator and the denominator.

Factoring \( f(x) \):

To factor \( f(x) = 2x^2 - x - 6 \), we look for two numbers that multiply to \( 2 \times -6 = -12 \) and add to \( -1 \). These numbers are \( -4 \) and \( 3 \).

Thus, we can rewrite \( f(x) \): \[ f(x) = 2x^2 - 4x + 3x - 6 \] Group terms: \[ f(x) = (2x^2 - 4x) + (3x - 6) = 2x(x - 2) + 3(x - 2) \] Factoring by grouping gives: \[ f(x) = (2x + 3)(x - 2) \]

Factoring \( g(x) \):

Now, we factor \( g(x) = x^2 + 3x - 10 \). We look for two numbers that multiply to \( -10 \) and add to \( 3 \). These numbers are \( 5 \) and \( -2 \).

Thus, we can factor \( g(x) \): \[ g(x) = (x + 5)(x - 2) \]

Combining the results:

Now substituting the factored forms back into \( \frac{f(x)}{g(x)} \): \[ \frac{f(x)}{g(x)} = \frac{(2x + 3)(x - 2)}{(x + 5)(x - 2)} \]

Simplifying:

The term \( (x - 2) \) is common in both the numerator and denominator, so we cancel it out: \[ \frac{f(x)}{g(x)} = \frac{2x + 3}{x + 5} \] This is valid as long as \( x \neq 2 \).

Finding the domain:

The domain of \( \frac{f(x)}{g(x)} \) is all the values of \( x \) for which \( g(x) \neq 0 \).

Setting \( g(x) = x^2 + 3x - 10 = 0 \): Factoring gives us: \[ (x + 5)(x - 2) = 0 \] Thus, \[ x + 5 = 0 \quad \Rightarrow \quad x = -5 \] \[ x - 2 = 0 \quad \Rightarrow \quad x = 2 \]

The function \( \frac{f(x)}{g(x)} \) is undefined at \( x = -5 \) and \( x = 2 \). Therefore, the domain of \( \frac{f(x)}{g(x)} \) is: \[ \text{Domain: } x \in \mathbb{R} \setminus {-5, 2} \]

So, in interval notation, the domain of \( \frac{f(x)}{g(x)} \) can be expressed as: \[ (-\infty, -5) \cup (-5, 2) \cup (2, \infty) \]