Does anyone know how to do functions?

Question

anonymous · Answer

I need help :/

imstuck · Answer

Because the vertex of the parabola is sitting at (0, -2) and the parabola is "upside down", it is a -x^2 parabola.  So far we have, then,$$f(x)=-x ^{2}$$This means that the parabola is upside down and the x coordinate is 0.  Because it has moved down the y axis, that is the coordinate we have to adjust.  We will use the fact that the signs are opposite of how the graph moves.  For example, if the graph doesn't move horizontally but moves vertically up 2, the coordinates for the vertex would be (0, -2).  See that so far?

imstuck · Answer

But since we have moved the y coordinate down, the vertex is at (0, 2).  Plugging that fact into the equation we have thus far makes the whole thing$$f(x)=-x ^{2}-2$$WAIT!!!! Hold the phone!  I made an error.

imstuck · Answer

Since this is a vertex and NOT a center, forget the sign change thing.  We are moving the y coordinate down, so the vertex is at (0, -2).  The equation is$$f(x)=-x ^{2}-2$$which tells us that it is a. upside down, b. sitting at x = 0, and c. moved down the y axis 2 units

imstuck · Answer

Sorry for the confusion.  Do you understand how I got the equation for this?  You only take into consideration the opposite sign when you are working with a change in x and y coordinates for circles or ellipses.

anonymous · Answer

i think i got a bit of the concept. @IMStuck. :)