I need to write the equation for a parabola that passes through the points (0,4),(-3,1) and has an axis of symmetry at x=-2
That's what you are to find- don't expect people to do the whole problem for you, you won't learn that way. skeeter did just tell you what h is: "h= x-value of vertex". You don't know what k (the y value of the vertex) is but you do h: "the parabola has an axis of symmetry at x= -2". Put in that value for h and you have an equation in a and k. Use the fact that (0,4) and (-3,1) are on the parabola, and so satisfy the equation, to get two equations to solve for a and k.