Đáp án:
`a. \frac{15^4 xx5^4}{25^5}`
`= \frac{3^4 xx5^4 xx5^4}{5^{10}}`
`= \frac{81xx5^4}{5^6}`
`= \frac{81}{5^2}`
`= 81/25`
`b. \frac{8^4}{12^3}`
`= \frac{2^{12}}{2^6 xx3^3}`
`= \frac{2^6}{3^3}`
`= 64/27`
`c. \frac{3^4 xx6^7}{4^6 xx9^3}`
`= \frac{3^4 xx2^7 xx3^7}{2^{12}xx3^6}`
`= \frac{3^7}{2^5 xx3^2}`
`= \frac{3^5}{32}`
`= 243/32`
`d. \frac{3^4+2xx6^2+9}{18}`
`= \frac{81+71+9}{18}`
`= 162/18`
`= 9`
