[填空题]
The graph shows the curve of a quadrg 9oy oa)nacd92js0gl9-;lgc atic function of th 4sq f-g9j.3vdw j g/e0l*vp*ct shws2e 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.
