(2x-1)的平方-（3x+1)(3x-1)+5x(x+1)
=(2x-1)^2-(9x^2-1)+5x^2+5x
=4x^2-4x+1-9x^2+1+5x^2+5x
=(4x^2-9x^2+5X^2)+(-4x+5x)+(1+1)
=x+2
其中x=2013
x+2
=2013+2
=2015