[tex]a)\\25*5^3*5^0=5^2*5^3*5^0=5^{2+3+0}=5^5\\b)\\\frac{1}{81} *\frac{1}{9} *\frac{1}{3} =\frac{1}{3^4} *\frac{1}{3^2} *\frac{1}{3} =\\\\=3^{-4}*3^{-2}*3^{-1}=3^{-7}=\frac{1}{3^7} \\c)\\\frac{9*3^9*\frac{27}{-3^7}}{3^4} =\frac{3^2*3^9*\frac{3^3}{-3^7} }{3^4} =\\\\=\frac{3^{11}*(-3^{-4})}{3^4} =\frac{3^{11}*(3^{-4})}{3^4}=3^{11-4-4}=3^3\\d)\\\frac{\frac{7^{11}}{49} }{7^4*7^3} =\frac{\frac{7^{11}}{7^2} }{7^7} =\frac{7^{11-2}}{7^7} =\\\\=\frac{7^9}{7^7}=7^2[/tex]
