Question

Cum determin imaginea functiei f: R--->R daca f(x)=-x^3+4x-1

Answer 1

Daca a>0
$f:[ \frac{-d}{4a}, +infinit)$
Daca a<0
$f:(-infinit, \frac{-d}{4a} ]$

d- delta

Tu ai a=-1 ⇒ a<0
$\frac{-d}{4a}= \frac{-(16-4)}{-4} = \frac{12}{4}=3$
f:(-∞, 3]