Разложите на множетили! х⁴-6х²+8 х³-4х²-125+20х 9-25х²+30ху-9у²

X⁴-6x²+8=x⁴-4x²-2x²+8=(x⁴-4x²)-(2x²-8)=x²(x²-4)-2(x²-4)=
=(x²-4)(x²-2)=(x-2)(x+2)(x²-2)

x³-4x²-125+20x=(x³-125)-(4x²-20x)=(x-5)(x²+5x+25)-4x(x-5)=
=(x-5)(x²+5x+25-4x)=(x-5)(x²+x+25)

9-25x²+30xy-9y²=9-(25x²-30xy+9y²)=3² - (5x-3y)²=
=(3-5x+3y)(3+5x-3y)