太麻烦
做一个
y=3x²+10x-8
=3（x²+10/3x+25/9)-8-3×25/9
=3(x+5/3)²-49/3
∵3x²+10x-8=(3x-2)(x+4)
∴两根式y=3(x-2/3)(x+4)