1)9x^2 - 25y^2=(3x-5y)(3x+5y),
9x^2+30xy+25y^2=(3x+5y)^2.
2)x2 - y2 = (x - y)(x + y)
x2 + y2 = здесь нет такой формулы
3) ((27*x^3+8*y^3)/(9*x^2-6*x*y+4*y^2))-3*x =((3*x+2*y)*(9*x^2-6*x*y+4*y^2))/(9*x^2-6*x*y+4*y^2)-3*x=(3*x+2*y-3*x)=2*y;
4)= (5x - 6y - 5x - 6y)(5x - 6y + 5x + 6y) =
= - 12y * 10x =
= - 120xy
5)4x+3y-36=0
3y=36-4x | /3
y=12-4x/3
x-6y+3=0
6y=x+3
y=x+3/6