3 ^ 68 = 18 ^ 16 75 ^ 20 = 5^120 esay qua bai nay krt ban nhe
a) ta có:128×912= (3×4)8 × (32)12
=38 × 48 × 324
=38 × (22)8 × 324
=38 × 216 × 324
=38 × 324 × 216
=332 × 216
=(32)16 × 216
=916 × 216
=(9×2)16
=1816
vậy 128 × 912 = 1816
a, ta có : 128.912=(3.22)8.(32)12
= 38.216.324
=332.216
=(32)16.216
=916.216
=(9.2)16=1816
Vậy 128.912=1816
b, 7520=4510.530
ta có : (52.3)20=(32.5)10.530
=> 540.320=320.510.530
=> 540.320=320.540
Vậy 7520=4510.530
