你说的应该是二次函数y=ax²+bx+c吧
y=ax²+bx+c
=a(x²+b/ax+(b/2a)²-(b/2a)²)+c
=a(x+b/2a)²+c-b²/4a
=a(x+b/2a)²+4ac/4a-b²/4a
=a(x+b/2a)²+(4ac-b²)/4a
你说的应该是二次函数y=ax²+bx+c吧
y=ax²+bx+c
=a(x²+b/ax+(b/2a)²-(b/2a)²)+c
=a(x+b/2a)²+c-b²/4a
=a(x+b/2a)²+4ac/4a-b²/4a
=a(x+b/2a)²+(4ac-b²)/4a