For which range of kkk does x2+kx+2=0x^2 + kx + 2 = 0x2+kx+2=0 have real solutions?
k≤−22k \leq -2\sqrt{2}k≤−22 or k≥22k \geq 2\sqrt{2}k≥22
−22≤k≤22-2\sqrt{2} \leq k \leq 2\sqrt{2}−22≤k≤22
k<−22k < -2\sqrt{2}k<−22
k>22k > 2\sqrt{2}k>22