Lesson Summary

Quadratic

-graph(parabola)
one turning point
line of symmetry( (X1+X2)/2 )
intercept to y ( c of y=ax^2+bx+c)
intercept to x  (X1 X2)
(a determine its shape)


-
(a+b)^2=a^2+2ab+b^2
a^2-b^2=(a+b)(a-b)


-function
(base on a vertical line test) <many to one>
basic form: ax^2+bx+c=0
roots:
    discriminant: D=b^2-4a
    D>0, real & different roots
    D=0, real & equal
    D<0, imaginary(complex root)
solving:
    cross method
    formula: x= ( -b+(-)√D )/ (2a)
    


sum of roots: -b/a
product of roots: c/a

x^2-(-b/a)x+c/a=0
x^2-(X1+X2)x+X1X2=0
x^2-(sum of roots)x+product of roots=0