2. a) 16 = $2^{4}$
b) -$\frac{27}{343}$ = (-$\frac{3}{7}$)$^{3}$
c) 0,0001= (0,1)$^{4}$
3. a) 243 = $3^{5}$
b) -$\frac{64}{125}$ = (-$\frac{4}{5}$)$^{3}$
c) 0,25 =($\frac{1}{2}$)$^{2}$
4. a) 2 . 16 . 8 = 2 . $2^{4}$ . $2^{3}$ = $2^{8}$
b) 25. 5 . 125 = $5^{2}$ . 5 . $5^{3}$ = $5^{8}$