Question

\(1.\)Tính

\(a)\frac{120^3}{40^3};\frac{390^4}{130^4};\frac{3^2}{0,375^2}\)

\(2.\)Tính giá trị các biểu thức sau :

\(a)\frac{45^{10}.5^{20}}{75^{15}}\) ; \(b)\frac{\left(0,8\right)^5}{\left(0,4\right)^6}\) ; \(c)\frac{2^{15}.9^4}{6^6.8^3}\)

Answer 1

1. sai dấu nhé 

2.a, \(\frac{45^{10}.5^{20}}{75^{15}}=\frac{\left(3^2.5\right)^{10}.5^{20}}{\left(5^2.3\right)^{15}}=\frac{3^{20}.5^{30}}{5^{30}.3^{15}}=3^5=243\)

b, \(\frac{\left(0,8\right)^5}{\left(0,4\right)^6}=\frac{\left(\frac{4}{5}\right)^5}{\left(\frac{2}{5}\right)^6}=\frac{\left(\frac{2}{5}\cdot2\right)^5}{\left(\frac{2}{5}\right)^6}=\frac{\left(\frac{2}{5}\right)^5\cdot2^5}{\left(\frac{2}{5}\right)^5\cdot\frac{2}{5}}=2^5\div\frac{2}{5}=32\cdot\frac{5}{2}=80\)

c, \(\frac{2^{15}.9^4}{6^6.8^3}=\frac{2^{15}.3^8}{2^6.3^6.2^9}=\frac{2^{15}.3^2}{2^{15}}=3^2=9\)