A particle \( P \) moves in a straight line so that, \( t \) seconds after passing a fixed point \( O \), its displacement, \( s \) metres, is given by \( s=4 t^{3}-15 t^{2}+18 t \). Find (i) the velocity of \( P \) when \( t=3 \), (ii) the acceleration of \( P \) when \( t=3 \), (iii) the values of \( t \) when \( P \) is at instantaneous rest, (iv) the distance travelled by \( P \) in the first 2 seconds of its motion, (v) the distance of \( P \) from \( O \) when \( t=2 \).

The area of a rectangular cross-section of a solid is given by the dimensions in terms of a linear function: width = \(x\) and height = \(3 - x\) for \(0 \leq x \leq 3\). Calculate the volume of the solid when these rectangles are stacked from \(x=0\) to \(x=3\).

\( f ( x ) = x ^ { 3 } - 4 x ^ { 2 } \rightarrow f ( 0 ) , f ( 1 ) , f ( - 1 ) , f ( \frac { 3 } { 2 } ) \)

\( f ( x ) = x ^ { 3 } - 4 x ^ { 2 } \rightarrow f ( 0 ) , f ( 1 ) , f ( - 1 ) , f ( \frac { 3 } { 2 } ) \)

Partie I : Théorème de Relèvement angulaire On donne \( g: \mathbb{R}^{+} \rightarrow \mathbb{C}^{*} \) de classe \( C^{k}, k \geq 2 \) 1. Justifier l'existence d'une primitive \( A \) de \( \frac{g^{\prime}}{g} \), et montrer que \( \mathbb{R}^{+} \rightarrow \mathbb{C}, t \mapsto g(t) e^{-A(t)} \) est constante. 2. On pose \( g(t) e^{-A(t)}=K_{0} \in \mathbb{C}^{*} \), en écrivant la fonction \( A \) sous la forme \( A=B+\mathrm{i} C \), où \( B \) et \( C \) sont des fonctions à valeurs réelles et \( K_{0}=r_{0} e^{i \alpha} \), justifier qu'existent \( r \in \mathcal{C}^{k}\left(\mathbb{R}^{+}, \mathbb{R}_{+}^{*}\right) \) et \( \theta \in \mathcal{C}^{k}\left(\mathbb{R}^{+}, \mathbb{R}\right) \) tels que : \[ \forall t \geq 0, g(t)=r(t) e^{i \theta(t)} \]

- Derivative of \( \tan x \) Solution