1)(3^5)⁴\3^6 *3¹¹ = 3^20 / 3^6 * 3^11 = 3^14 * 3^11 = 3^25
2)-5х²у²*0,04х²у² = -1 * 5х²у² * 5^-2 * х²у² = -1 * 5^-1 * x^4 * y^4 = -0,2x^4 * y^4
3)(-2х³у²)² * х²у³ = (-2)^2 * x^6 * y^4 * х²у³ = 4*x^8 * y^7
4)(а-9b)+(9a-2b)-(8a-6b) = a-9b + 9a - 2b - 8a + 6b =2a - 5b