用配方法把y=-1/2x^2+2x-1化为y=a(x-h)2+k的形式

Question

用配方法把y= -1/2x^2+2x-1 化为y=a(x-h)2+k的形式

Answer 1

y= -1/2x^2+2x-1
=-1/2(x^2-4x+4)+1
=-1/2(x-2)^2+1