Question

Which equation can be used to describe g(x) in terms of f(x)?

Answer 1

F(x) is a parabola opening upward, while g(x) is a parabola facing downward.

So there needs to be a negative out front of the f(x) term. The negative will flip the parabola. That means the answer is either A or B

-----------------------

After we flip the parabola, we need to translate the vertex (0,0) to the point (2,1) so that it matches up with the vertex of g(x)

To move from (0,0) to (2,1) we shift 2 units to the right and 1 unit up. 

To move 2 units to the right, replace 'x' with 'x-2'
To move 1 unit up, you tack on a "+1"

So f(x) turns into -f(x) and then we replace the x with x-2 to get -f(x-2). Finally we tack on a "+1" to get -f(x-2)+1

The g(x) function is g(x) = -f(x-2)+1

----------------------------

Therefore the final answer is choice B