Question

二次函数y=ax2+bx+c顶点推导过程,

Answer 1

y=a(x²+bx/a)+c

=a(x²+bx/a+b²/4a²-b²/4a²)+c

=a(x²+bx/a+b²/4a²)-b²/4a+c

=a(x+b/2a)²+(4ac-b²)/4a

所以顶点是[-b/2a,(4ac-b²)/4a]