求2a的平方-5a-2+a的平方+1分之3
x^2-3x+1=0的根 a= 3/2±5^0.5/2
2a^2-5a-2+a^2+1/3=3a^2-9a+1+4a-3+1/3=4a-8/3=6±2*5^0.5-8/3=10/3±2*5^0.5