determinati inf f(x) si sup f(x) pentru f:E→R in cazurile:
1) f(x)=3x +2 ,E=[-1, 2]
2) f(x)=x² -2x , x∈[-1, 3]
3) f(x)=sin x +1 , x∈[0, π/4]
4)f(x)=3⁻ˣ -1, x∈[-1, 1]