[填空题]
The graph shows the curv5 *y6.vu ) sgdkxgf5hne of a quadratic fun2,kgsw3djkn 5 ction of the form $ f(x)=a x^{2}+b x+90 $.
1. Write down the equation for the axis of symmetry of the curve.
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.
