Question

y=x^2-2x-1 y=-（x-2）（x+3）用配方法或公式法求顶点坐标

Answer 1

解

y=x²-2x-1

=(x²-2x+1)-1-1

=(x-1)²-2

顶点(1,-2)

y=-(x-2)(x+3)

=-(x²+x-6)

=-(x²+x)+6

=-(x²+x+1/4)+1/4+6

=-(x+1/2)²+25/4

顶点(-1/2,25/4)