2x^2+5x-2=0 x^2+5x/2-1=0 x+5/2-1/x=0 x-1/x=-5/2 (x+1/x)^2=(x-1/x)^2+4 (x+1/x)^2=(-5/2)^2+4 (x+1/x)^2=25/4+4 (x+1/x)^2=41/4 x+1/x=±√41/2
