Let f(x)=tan(ax)−sin(ax)x3f(x) = \frac{\tan(ax) - \sin(ax)}{x^3}f(x)=x3tan(ax)−sin(ax). What value must aaa take such that limx→0f(x)=14\lim_{x \to 0} f(x) = \frac{1}{4}limx→0f(x)=41?
a=1a=1a=1
a=2a=\sqrt{2}a=2
a=2a=2a=2
a=3a=\sqrt{3}a=3