[tex]\it a)\ \ x*0=3x\cdot0+7x+7\cdot0+14=7x+14\ \ \ \ \ (1)\\ \\ 1*2=3\cdot1\cdot2+7\cdot1+7\cdot2+14=6+7+14+14=41\ \ \ \ \ (2)\\ \\ (1),\ (2)\ \Rightarrow\ (1*2)*0=41*0=7\cdot41+14=287+14=301\\ \\ \\ f)\ \ x*x=3\cdot x\cdot x +7x+7x+14=3x^2+14x+14[/tex]
[tex]\it Fie\ \ f(x)= 3x^2+14x+14 \Rightarrow x_m=-\dfrac{14}{2\cdot3} \Rightarrow x_m=-\dfrac{7}{3}[/tex]
[tex]\it\ Deci,\ f(x)\ \geq-\dfrac{7}{3},\ \forall\ x\in \mathbb{R}\\ \\ Inecua\c{\it t}ia\ f(x)\leq-\dfrac{7}{3}\ are\ o\ singur\breve a\ solu\c{\it t}ie:\ \ x=-\dfrac{7}{3}[/tex]
