10√(x^3+1) = 3(x^2+2) (x/x+1)^2 + (x/x-1)^2 = 10/9 căn bậc 3(x+1) + căn bậc 3(x+2) + căn bậc 3(x+3) = 0 √(x-(1/x)) + √(1-(1/x)) = (x-1)/x