Rút gọn: a)\(\frac{2^{19}.27^3+15.4^9.9^4}{6^9.2^{10}.12^{10}}\)
b)\(\frac{\left(-\frac{1}{2}\right)^3-\left(\frac{3}{4}\right)^3.\left(-2\right)^2}{2.\left(-1\right)^5+\left(\frac{3}{4}\right)^2-\frac{3}{8}}\)
Tìm x
a)\(3^{x+1}=9^x\)
b)\(2^{3x+2}=4^{x+5}\)
c)\(3^{2x-1}=243\)