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Posted: **Tue Jun 09, 2009 4:00 pm**

Determinati \( a\in\mathbb{N}^{*} \) si \( b,c,d\in\mathbb{R} \) astfel incat:

\( |ax^3+bx^2+cx+d|\leq 2, \ \forall\ x\in [-2,2]. \)

Posted: **Thu Jan 21, 2010 10:41 pm**

Notand \( f(x)=ax^3+bx^2+cx+d \) avem

\( 12a=|f(2)-f(-2)-2f(1)+2f(-1)|\le 12 \) de unde \( a=1 \)

Functie de grad 3