解x³-7x²-17x-9=0,

解x³-7x²-17x-9=0,

y(x)=x^3-7x^2-17x-9=0(1)
y=x^3-7x^2-17x-9
=(x+1)(x^2-8x-9)
=(x-9)(x+1)=0(2)
すなわち:
x1,2=-1(2重根)x3=9(3)