Question

求一元二次方程推导式

Answer 1

ax^2+bx+c=0

x^2+b/a=-c/a

x^2+b/a+(b/2a)^2=-c/a+b^2/4a^2

(x+b/2a)^2=(b^2-4ac)/4a^2

x+b/2a=土√b^2-4ac/2a

x=-b土√b^2-4ac/2a

acx^2+(bd+ac)x+bd=0

则（ax+b）（cx+d）=0

祝愉快