Given the graph of f(x)=(x−4)2+2 , which of the options is the graph of −f(x) ?

1 answer

To find the graph of \(-f(x)\) given \(f(x) = (x - 4)^2 + 2\), we first need to understand what \(-f(x)\) represents.

Starting with the function:

\[ f(x) = (x - 4)^2 + 2 \]

Now, to find \(-f(x)\):

\[ -f(x) = -[(x - 4)^2 + 2] = -(x - 4)^2 - 2 \]

This means that the graph of \(-f(x)\) is obtained by taking the original graph of \(f(x)\) and reflecting it across the x-axis, and then shifting it down by 2 units.

  1. Reflection:

    • The graph of \(f(x)\) opens upwards since it is a quadratic function with a positive leading coefficient. Reflecting it across the x-axis will make it open downwards.
  2. Shift Down:

    • The entire graph of the reflected function is then shifted down by 2.

Key Points about the Graph of \(-f(x)\):

  • The vertex of the original function \(f(x)\) is at \((4, 2)\).
  • Reflecting the vertex \((4, 2)\) across the x-axis gives \((4, -2)\).
  • Shifting this point down by 2 yields the new vertex at \((4, -2 - 2) = (4, -4)\).
  • The graph will open downwards from this vertex.

If you have specific options to choose from, the graph you are looking for will be a downward-opening parabola with its vertex at \((4, -4)\). It will also be symmetrical about the vertical line \(x = 4\).

Make sure to look for these characteristics when examining the options for the graph of \(-f(x)\).