y=a(x-h)²+k
则顶点是(h,k),对称轴x=h
(1)
y=2(x²-4x+4)-7
=2(x-2)²-7
所以顶点是(2,-7),对称轴x=2
(2)
y=-0.5(x²-2x+1)-1
=-0.5(x-1)²-1
所以顶点是(1,-1),对称轴x=1