сократите дробь
1) 12x^2-4x/2-6x
2) x^2-9/x^2+6x+9
3) b^7+b^4/b^2+b^5

1) 12х^2-4х/2-6х=4х(3х-1)/2(1-3х)=2х(3х-1)/(1-3х)=-2х(3х-1)/(3х-1)=-2х

2) х^2-9/х^2+6х+9=(х-3)(х+3)/(х+3)^2=(х-3)/(х+3)

3) b^7+b^4/b^2+b^5=b^4(b^3+1)/b^2(1+b^3)=b^4/b^2=b^2