254 . 28 = 58 . 28 = 108

158 . 94 = 158 . 38 = 458

108 : 28 = (10:2)8 = 58

272 : 253 = (33)2 : (52)3 

= 33.2 : 52.3

 = 36 :  5 6 = 3 5 6

a) \(15^8\cdot2^4\)

\(=\left(15^2\right)^4\cdot2^4\)

\(=225^4\cdot2^4\)

\(=\left(225\cdot2\right)^4\)

\(=450^4\)

b) \(27^5:32^3\)

\(=\left(3^3\right)^5:\left(2^5\right)^3\)

\(=3^{15}:2^{15}\)

\(=\left(\dfrac{3}{2}\right)^{15}\)

Bài 6: 

a: \(2^{27}=8^9\)

\(3^{18}=9^9\)

b: Vì \(8^9< 9^9\)

nên \(2^{27}< 3^{18}\)

25⁴ . 2⁸ = (5²)⁴ . 2⁸ = 5^2.4 . 2⁸ = 5⁸ . 2⁸ = (5 . 2)⁸ = 10⁸

25⁴.2⁸=(5²)⁴.2⁸=5⁸.2⁸=(5.2)⁸=10⁸=100000000

=10.2>8=20>8