$u= \sin ^{-1} \bigg(\large\frac{x^4+y^4}{x+y}\bigg)$$=> x \large\frac{du}{dx}$$+y \frac{du}{dy}=$

Question

\[\begin {array} {1 1} (1)\;3u & \quad (2)\;4u \\ (3)\;3 \sin u & \quad (4)\;3\; \tan u \end {array}\]