Find the value of kkk such that the parabola y=2x2+kx+8y = 2x^2 + kx + 8y=2x2+kx+8 is tangent to the xxx-axis.
k=4k = 4k=4
k=8k = 8k=8 or k=−8k = -8k=−8
k=2k = 2k=2 or k=−2k = -2k=−2
k=16k = 16k=16 or k=−16k = -16k=−16