1) 25y-y^3=y(25-y^2)=y(5-y)(5+y)
2) 20x+5(x-2)^2=20x+5(x^2-4x+4)=20x+5x^2-20x+20=5x^2+20=5(x^2+4)
3) (x-3)^2-16=0
(x-3)^2=16
x-3 = 4 x-3=-4
x= 7 x=-1
16ab^2 - 5b^2c-10c^3+32ac^2=16a(b^2+c^2)-5c(b^2+2c^2)=(b^2+c^2)(16a-5c)
4х^2+6х+16х+24-(4х^2+4х+1)
4х^2+6х+16х+24-4х^2-4х-1