${d \over {dx}}\left( {{1 \over {{x^4}\sec x}}} \right) = $

  • A
    ${{x\sin x + 4\cos x} \over {{x^5}}}$
  • B
    ${{ - (x\sin x + 4\cos x)} \over {{x^5}}}$
  • C
    ${{4\cos x - x\sin x} \over {{x^5}}}$
  • D
    None of these

Similar Questions

A river is flowing from east to west at a speed of $5\ m/min$ . A man on south bank of river, capable of swimming $10\ m/min$ in still water, wants to swim across the river in shortest time. He should swim

$A =2 \hat{ i }+\hat{ j }, B =3 \hat{ j }-\hat{ k }$ and $C =6 \hat{ i }-2 \hat{ k }$ Value of $A -2 B +3 C$ would be

If the angle between two vectors $A$ and $B$ is $120^{\circ}$, its resultant $C$ will be

A boat is sent across a river with a velocity of $8\, km/hr$. If the resultant velocity of boat is $10 \,km/hr$, then velocity of the river is ........$km/hr$

Given $A =\hat{ i }+\hat{ j }+\hat{ k }$ and $B =-\hat{ i }-\hat{ j }-\hat{ k }$, then $( A - B )$ will make angle with $A$