[tex]a \cdot b = -\frac{2}{5} [/tex]
[tex]a \cdot c = \frac{1}{3}[/tex]
[tex]A) a \cdot (b+c) = ab + ac = -\frac{2}{5} + \frac{1}{3} = \frac{-6+5}{15} = \frac{-1}{15}[/tex]
[tex]B) a \cdot (b-c) = ab - ac = -\frac{2}{5} - \frac{1}{3} = \frac{-6-5}{15} = \frac{-11}{15} [/tex]
