Question

k>=9 解方程x^3+2kx^2+k^2*x+9k+27=0

Answer 1

x³+2kx²+k²x+9k+27=0x²(x+k+3)+(k-3)x²+k²x+9(k+3)=0x²(x+k+3)+(k-3)x(x+k+3)+9x+9(k+3)=0x²(x+k+3)+(k-3)x(x+k+3)+9(x+k+3)=0(x+k+3)(x²+(k-3)x+9)=0x1=-k-3,x2=(3-k...