Ответ:

  1. \(\frac{15^9\cdot15^5}{15^{13}}=15^{9+5-13}=15=15\).
  2. \(5^{15}\cdot5^{-17}\cdot5^4=5^{15-17+4}=5^2=25\).
  3. \(\frac{0.4^{11}}{0.4^4\cdot0.4^5}=0.4^{11-4-5}=0.4^2=0.16\).
  4. \(8^{-2}\cdot4^3=\frac1{8^2}\cdot4^3=\frac1{64}\cdot64=1\).
  5. \(9^0:9^{-2}=9^{0-(-2)}=9^2=81\).
  6. \(7^8\cdot7^{-5}\cdot7^{-4}=7^{8-5-4}=7^{-1}=\frac17\).

Жауап: 1) 15; 2) 25; 3) 0.16; 4) 1; 5) 81; 6) \(\frac17\).