6.
[tex]R = 2 \ m\\\\f = \frac{1}{2}R = \frac{1}{2}\cdot2 \ m =-1 \ m \ \ (ogniskowa \ zwierciadla \ wypuklego \ jest \ ujemna)\\\\Z = \frac{1}{f}\\\\Z = \frac{1}{-1 \ m}\\\\\boxed{Z = -1 \ D}\\\\\underline{Odp. \ D.}[/tex]
7.
[tex]D = 3 \ D\\\\D = \frac{1}{f} \ \ \rightarrow \ \ f = \frac{1}{D}\\\\f = \frac{1}{3} \ m\\\\R = 2f = 2\cdot\frac{1}{3} \ m\\\\\boxed{R = \frac{2}{3} \ m}\\\\\underline{Odp. \ C.}[/tex]
