Найдите нули функции

1) у=х^3-x^2-x+1

2) y=8x^4-125x

3) y=2x^5+54x^2

1) y=xˇ3-xˇ2-x+1=xˇ2 (x-1) - (x-1).1 = (x-1) (xˇ2-1) = (x-1) (x+1) (x-1)

x1=1, x2=-1 y (1) y (-1) = 0

2) y=8x4-125x = x (8xˇ3-125) = x ((2x) ˇ3-5ˇ3) = x (2x-5) (4xˇ2+10x+25)

x1=0, x2=5/2

(4xˇ2 + 10x+25 položitelnoe dlja x iz R)

3) y=2xˇ5+54xˇ2=2xˇ2 (xˇ3+27) = 2xˇ2 (xˇ3+3ˇ3) =

=2xˇ2 (x+3) (xˇ2-3x+9)

x1=0, x2=-3 (xˇ2-3x+9 položitelnoe dlja bcjakogo x iz R)