7. Integrate
(A) $\int \frac { x ^ { 3 } + 3 x + 2 } { \left( x ^ { 2 } + 1 \right) ^ { 2 } ( x + 1 ) } \mathrm { dx }$.
(B) $\quad \int _ { 0 } ^ { \pi } \frac { e ^ { \cos x } } { e ^ { \cos x } + e ^ { - \cos x } } \mathrm { dx }$. 8. Let $\mathrm { f } ( \mathrm { x } )$ be a continuous function given by
$$f ( x ) = \left\{ \begin{array} { c c }
2 x , & | x | \leq 1 \\
x ^ { 2 } + a x + b , & | x | > 1
\end{array} \right.$$
Find the area of the region in the third quadrant bounded by the curves $x = - 2 y 2$ and $y = \mathrm { f } ( \mathrm { x } )$ lying on the left on the line $8 \mathrm { x } + 1 = 0$. 9. Find the co-ordinates of all the P on the ellipse $\mathrm { x } 2 / \mathrm { a } 2 + \mathrm { y } 2 / \mathrm { b } 2 = 1$, for which the area of the triangle PON is maximum, where O denotes the origin and N , the foot of the perpendicular from O to the tangent at P . 10. A curve passing through the point $( 1,1 )$ has the property that the perpendicular distance of the origin from the normal at any point P of the curve is equal to the distance of P from the x -axis. Determine the equation of the curve. 11. Eight players $\mathrm { P } 1 , \mathrm { P } 2 , \ldots \ldots . \mathrm { P } 8$ play a knock-out tournament. It is known that whenever the players Pi and Pj play, the play Pi will win if $\mathrm { i } < \mathrm { j }$. Assuming that the players are paired at random in each round, what is the probability that the player P4 reaches the final? 12. Let $\vec { u }$ and $\vec { v }$ be unit vectors. If $\vec { w }$ is a vector such that $\vec { w } + ( \vec { w } \times \vec { u } ) = \vec { v }$, then prove that $| ( \vec { u } \times \vec { v } ) \cdot \vec { w } | \leq \frac { 1 } { 2 }$ and that the equality holds if and only if $\vec { u }$ is perpendicular to $\vec { v }$.