a) 64$^x$:16$^x$=256 b)$\frac{1}{9}^6.\frac{1}{3}^3$

Quỳnh Anh

$a,64^x:16^x=256$

$\left(64:16\right)^x=256$

$4^x=256$

$4^x=4^4$

$x=4$

Vậy: $x=4$

$b,\left(\frac{1}{9}\right)^6\cdot\left(\frac{1}{3}\right)^3=\left\lbrack\left(\frac{1}{3}\right)^2\right\rbrack^6\cdot\left(\frac{1}{3}\right)^3=\left(\frac{1}{3}\right)^{12}\cdot\left(\frac{1}{3}\right)^3=\left(\frac{1}{3}\right)^{15}$