4 mũ 2 = 2 mũ 3 nên 2 mũ 15. 4 mũ 2 = 2 mũ 15. 2 mũ 3 = 2 mũ 18
3 mũ 2 =9 mũ 1 nên9 mũ 12.3 mũ 2 =9 mũ 12. 9 mũ 1 = 9 mũ 11
225.42= 225 . (22)2 = 225. 24 = 229
912: 32 = (32)12: 32= 324: 32 = 322
a.215.42=215.24=219
b.912:32=324:32=322
\(2^{15}\cdot4^2=2^{15}\cdot\left(2^2\right)^2=2^{15}\cdot2^4=2^{19}\)
\(9^{12}\cdot3^2=\left(3^2\right)^{12}\cdot3^2=3^{24}\cdot3^2=3^{26}\)
a.215.42
42=(22)2=24
215.24=215+4
=219
b.912:32
912=(32)12=314
314:32=314-2
=312
. D. 29.