3. Find the greatest and least values of the function $y=x^{3}-3 x^{2}+5$ on the interval $[-1 ; 1]$.
Solution: $y=x^{3}-3 x^{2}+5$ on $[-1 ; 1], y^{\prime}=3 x^{2}-6 x=0,3 x(x-2)=0, x=0 ; x=2$, $y(-1)=1 ; y(1)=3 ; y(0)=5$. Answer: $5 ; 1$.