f(x) = ax2 + bx +c
A= b2 - 4ac
a#0
-b
A= 0 jedno m.zerowe xb = ^
A> 0 dwa m. zero we
-b-VA -b+VA
x1 =
2a X2 “ 2a y=ax2+bx+c
b
y=a(*+ )2 ■
Postać iloczynowa:
A< 0 <f> {brak}
A_
4a
A= 0
A> 0
Wzory Viete’a:
y = a( X-Xb)2 y = a(x-x1)(x-x2)
Xi + x2 = Xi * x2 =
-b
a
c
a
X| i x2 jest:
- tego samego znaku gdy
- różnych znaków gdy
- oba dodatnie gdy
- oba ujemne gdy
Xi * x2 > O Xi * x2 < O Xi + x2 > O i Xi + x2 < O i
Xj + x2
Xi * x2 > O Xi * x2 > O
Xi x2
x2i +x22 = (Xi + x2)2-2XiX2 J_ J_ x2i + x22 _ fxi +x2)2 -2XjX2 X21+X22 ~ X2i * X22 " (Xi*X2)2
Xgu--
b
2a
)fw--
A
4a