Determine the value of kkk such that limx→0cos(kx)−1x2=−2\lim_{x \to 0} \frac{\cos(kx) - 1}{x^2} = -2limx→0x2cos(kx)−1=−2.
k=1k = 1k=1
k=2k = 2k=2
k=4k = 4k=4
k=2k = \sqrt{2}k=2