#1
3a²bc/18abc³=a/6c²
#2
39p^5q^8/65p^8q^5=3q³/5p³
#3
(b^5-b³)/(b²-b⁴)=b³(b²-1)/b²(1-b²)=-b³(1-b²)/b²(1-b²)=-b³/b²=-b
Sin(X)sin(2X)-sin(3X) - cos(X)cos(2X) = -(cos(X)cos(2X )- sin(X)sin(2X)) - sin(3X) = - cos(x+2x) - sin(3x) = -(sin3x + cos3x)
D=1-4*2*(-3) = 25
х1=1+5/4=3/2
х2=1-5/4= -1
Ответ: х1= 3/2, х2=-1