在一元二次方程中,b平方 | b平方4ac
![在一元二次方程中,b平方](https://i.imgur.com/axBPWDg.jpg)
ax2+bx+c=0a032313133353236313431303231363533e78988e69d8331333332643239ԣx-b/2a)2=(b2-4ac)/(4a24a2ΪԾ۳Y=aX2+bX+C=a(X+b/2a)2+(4ac-b2)/4aax2+bx+c=a(x2+b/2a)2-b2/4a+c=a(x2+b/2a)2-(b2-4ac)/4a=0(x2+b/2a)2=(b2-4ac)/4a2b2-4ac>=0ʱʵ֤£⣺裺УԪηax2bxc0a0ax2bxc0ax2bxc0ax2bxb/22b2/4ac0ax2b/22b2/4acax2b/22b24ac/4ax2b/22b24ac/4a24a2>0,൱b24ac0ʱԭн⣬x2b/22<0ԭ⡣κġôax2bxc0DzǴb2-4ac<0,ߴ0ұС0Ͳ䷽ͿԵõb2-4ac0(b2-4ac)/(4a202Ƚb2-4ac=0(b2-4ac)/(4a2=02Ƚb2-4ac0(b2-4ac)/(4a20жϸԼм䷽Լһȫƽ=B2-4AC/4AһƽС0ֻB2-4AC0ʵ
![在一元二次方程中,b平方](https://i.imgur.com/H8YKUrg.jpg)
Y=aX2+bX+C= a(X+b/2a)2 +(4ac - b2)/4a
ax2+bx+c=a(x2+b/2a)2-b2/4a+c=a(x2+b/2a)2-(b2-4ac)/4a=0(x2+b/2a)2=(b2-4ac)/4a2b2-4ac>=0ʱʵ
֤£⣺裺УԪηax2bxc0a0ax2bxc0ax2bxc0ax2bxb/22b2/4ac0ax2b/22b2/4acax2b/22b24ac/4ax2b/22b24ac/4a24a2>0,൱b24ac0ʱԭн⣬x2b/22<0ԭ⡣
κġô
ax2bxc0 DzǴ
b2-4ac<0,ߴ0ұС0Ͳ
䷽ͿԵõ
b2-4ac0(b2-4ac)/(4a202Ƚb2-4ac=0(b2-4ac)/(4a2=02Ƚb2-4ac0(b2-4ac)/(4a20
жϸԼм
䷽ Լ һȫƽ=B2-4AC/4AһƽС0 ֻB2-4AC0ʵ