[tex]1)\:f:\mathbb{R}\rightarrow\mathbb{R}, \: f(x) =x^2-3x+2\\\\a)\:f(-1) = (-1)^2-3\cdot(-1)+2=1+3+2=6\\f(2) = 2^2-3\cdot2+2=4-6+2=0\\f(-1) + f(2) = 6+0=6\\\\b) f(1) = 1-3+2=0\Rightarrow f(-1)\cdot f(0)\cdot f(1) = 0[/tex]
[tex]2)\:f(x) = 0\Leftrightarrow -3x^2+7x-2=0\\\Delta = 7^2-4\cdot3\cdot2 = 49-24=25\\\displaystyle x_{1,2}=\frac{-7\pm5}{-6}\Rightarrow x_1=2,\:x_2 = \frac{-2}{-6}=\frac{1}{3}[/tex]
