1) If y = tan−14x1+5x2+tan−12+3x3−2x then dydx = A) 11+25x2+21+x2 B) 51+25x2+21+x2 C) 51+25x2 D) 11+25x2 Answer: Option CExplanation:y = tan−14x1+5x2+tan−12+3x3−2x = tan−15x−x1+5x.x+tan−123+x1−23.x =tan−15x−tan−1x+tan−123+tan−1x then dydx = 51+25x2