0.49b^2-25=(0,7b-5)*(0,7b+5) 25-0,16y^2=(5-0,4y)*(5+0,4y) 8-x^6=(2-x^2)*(4+2x^2+x^4) -72xy^2+2xz^2=-2x(6y-z)*(6y+z)