解由y=ax^2+bx+c
=a[x^2+b/ax+c/a]
=a[x^2+b/ax+(b/2a)²-(b/2a)²+c/a]
=a[(x^2+b/2a)²-b²/4a²+c/a]
=a[(x^2+b/2a)²-b²/4a²+4ac/4a²]
=a[(x^2+b/2a)²+(4ac-b²)/4a²]
=a(x^2+b/2a)²+(4ac-b²)/4a
解由y=ax^2+bx+c
=a[x^2+b/ax+c/a]
=a[x^2+b/ax+(b/2a)²-(b/2a)²+c/a]
=a[(x^2+b/2a)²-b²/4a²+c/a]
=a[(x^2+b/2a)²-b²/4a²+4ac/4a²]
=a[(x^2+b/2a)²+(4ac-b²)/4a²]
=a(x^2+b/2a)²+(4ac-b²)/4a