x^3-5x^2 5x 5=0这是个一元三次方程,用盛金公式得三个根：x1=(5-(100^(1/3) 10^(1/3))/3x2=(5 sin30°[100^(1/3) 10^(1/3)] cos30°[100^(1/3)-10^(1/3)]i)/3x3=(5 sin30°[100^(1/3) 10^(1/3)]-cos30°[100^(1/3)-1...