[tex]\\(a)\\2^3 \times 2^6 \div 2^9 = 2^{3+6} \times \dfrac{1}{2^9} = 2^9 \times 2^{-9} = 2^{9-9} = 2^0 = 1\\\\ \\(b)\\\\(-5)^8 \div (-5)^4 \times (-5)^3\\ \\= (-5)^8 \times \dfrac 1{(-5)^4 \times (-5)^3} \\\\= (-5)^8 \times \dfrac{1}{(-5)^{4+3}} \\\\= (-5)^8 \times \dfrac{1}{(-5)^7} \\\\= (-5)^{8 - 7} \\\\=(-5)^1 \\\\ =-5\\\\\\(c)\\\\\\\dfrac{6^3 \times 6^5}{6^2 \times 6^4}= \dfrac{6^{3+5}}{6^{2+4}}= \dfrac{6^8}{6^6}=6^{8-6}=6^2 =36[/tex]
