Q. Consider, $f ( x )=\begin{vmatrix} x ^3-4 x & \sin x -\tan x & \sec ^2 x \\ 3 a ^2+1 & 2 a & a ^6+6 \\ a + k & 1 & 2\end{vmatrix}$. If $\int\limits_{\frac{-\pi}{4}}^{\frac{\pi}{4}} f(x) d x \geq 0 \forall a \in R$ then number of integral values of $k$ is(are) -
Integrals
Solution: