5x^2+x=2+x√(5x^2-1) 5x^2-x√(5x^2-1) = 2-x(5x^2-1) - x√(5x^2-1) = 1 - x(5x^2-1) - x√(5x^2-1) +x^2/4 = x^2/4 - x +1{ 根号(5x^2-1) - x/2}^2 = (x/2 -1)^2根号(5x^2-1) = x/2 ± (x/2 -1) = x - 1,或1（一...