[填空题]
The graph shows the curve of a quadratidx+r 0r *aydr;c function of the form f(luzij,fm 5h2azs7(w .,jl 1r )ojtyp0 x)=$ax^2$+bx+90.
1.Write down the equation for the axis of symmetry of the curve. x =
2.Hence, or otherwise, find the value of a and the value of b. a = b =
3.Find the y-coordinate of the vertex of the curve. f(x) =