Which graph represents the function of f(x) = the quantity of 4 x squared minus 4 x minus 8, all over 2 x plus 2?

graph of 2 x minus 4, with discontinuity at negative 1, negative 6
graph of 2 x minus 4, with discontinuity at 1, negative 2
graph of 2 x plus 2, with discontinuity at negative 1, 0
graph of 2 x plus 2, with discontinuity at 1, 4

1 answer

To analyze the function \( f(x) = \frac{4x^2 - 4x - 8}{2x + 2} \), we will first simplify it.

  1. Factor the numerator: \[ 4x^2 - 4x - 8 = 4(x^2 - x - 2) \] The quadratic \( x^2 - x - 2 \) can be factored further: \[ x^2 - x - 2 = (x - 2)(x + 1) \] Therefore, the numerator becomes: \[ 4(x - 2)(x + 1) \]

  2. Factor the denominator: The denominator can be factored as: \[ 2x + 2 = 2(x + 1) \]

  3. Rewrite the function: Now we can write \( f(x) \) as: \[ f(x) = \frac{4(x - 2)(x + 1)}{2(x + 1)} \] For \( x \neq -1 \), we can simplify this to: \[ f(x) = \frac{4(x - 2)}{2} = 2(x - 2) = 2x - 4 \]

  4. Identify the discontinuity: The function \( f(x) = 2x - 4 \) is defined everywhere except at \( x = -1 \). At \( x = -1 \), the original function has a removable discontinuity since the term \( (x + 1) \) cancels out.

  5. Find the value of \( f(-1) \): To find the value of the function at the discontinuity: \[ f(-1) = 2(-1) - 4 = -2 - 4 = -6 \]

Therefore, the graph of \( f(x) = 2x - 4 \) has a discontinuity at \( x = -1 \), with the point of discontinuity being \( (-1, -6) \).

Thus, the correct answer is the graph of \( 2x - 4 \), with discontinuity at \( (-1, -6) \).