1. (x+y)*x-x²-2xy=x²+xy-x²-2xy=-xy=-√12*√3=-√36=-6.
2. 8a³ab⁵/(12a²b³)=(8/12)*a⁴b⁵/(a²b³)=(3/4)*a²b²=0,75a²b².
3. √(3-a) ОДЗ: 3-a≥0 a≤3 ⇒ a∈(-∞;3].
4. (1-4a/(a²+4)*(a²+4)=((1*(a²+4)-4a)/(a²+4))*(a²+4)=a²-4a+4=(a-2)²=
=(2-√11-2)²=(-√11)²=11.
5. (2x-7)/(5-3x)=(-1)*(2x-7)/((-1)*(5-3x))≡(7-2x)/(3x-5).
Ответ:3).