Bài 6.17:
a) $(\dfrac{1}{7})$$^{7}$ $\text{. 7 $^{7}$ = $(\dfrac{1}{7}$ . 7)$^{7}$ = 1$^{7}$ = 1}$
b) $\text{(0,125)$^{3}$ . 512 = (0,125)$^{3}$ . 8$^{3}$ = (0,125 . 8)$^{3}$ = 1$^{3}$ = 1}$
c) $\text{(0,25)$^{4}$ . 1024 = (0,25)$^{4}$ . 4$^{4}$ . 4 = (0,25 . 4)$^{4}$ . 4 = 4}$
Bài 6.18:
a) $\dfrac{90^{3}}{15^{3}}$ $\text{=}$ $(\dfrac{90}{15})$$^{3}$ $\text{= 216}$
b) $\dfrac{790^{4}}{79^{4}}$ $\text{($\dfrac{790}{79}$)$^{4}$}$ $\text{= 10000}$
c) $\dfrac{3^{2}}{(0,375)^{2}}$ $\text{=}$ $(\dfrac{3}{0,375})^{2}$ $\text{= 8$^{2}$ = 64}$
Bài 6.19:
a) $\text{2$^{6}$ . 5$^{6}$ = (2 . 5)$^{6}$ = 1000000}$
b) $\text{4$^{3}$ . 5$^{3}$ = (4 . 5)$^{3}$ = 8000}$
c) $\text{6$^{3}$ . 5$^{3}$ = (6 . 5)$^{3}$ = 27000}$
d) $\text{8$^{2}$ . 5$^{2}$ = (8 . 5)$^{2}$ = 1600}$
e) $\text{125$^{3}$ . 8$^{3}$ = (125 . 8)$^{3}$ = 1000000000}$
f) $\text{5$^{2}$ . 6$^{2}$ . 3$^{2}$ = (5 . 6 . 3)$^{2}$ = 8100}$
