(a) \( [6 \) marks \( ] \) Find the general solution of the differential equations (i) \( x \cos ^{4} y d x+\tan y d y=0 \)

Determine the first derivative of the \( 1.1 \quad y=x^{3}-\cot \left(x^{3}+3 x-1\right) \)

1) Sout \( x>0 \). En appliquant le thécorème des accroissement fines à la fonction \( \ln \) montrer que: \( \exists c \in] x, x+1\left[\frac{1}{c}=\ln \left(1+\frac{1}{x}\right)\right. \) 2) \( M q: \exists c \in] 0, x\left[\right. \) arctan \( (x)=\frac{x}{1+c^{2}} \) 3) En déduire que \( \forall x>0: \) \( \frac{1}{1+x}<\ln \left(1+\frac{1}{x}\right)<\frac{1}{x} \)

Choose the correct answer from those givens: (1) If \( \operatorname{Lim}_{x \rightarrow 0} \frac{\cos x-\cos ^{a} x}{x^{2}}=1 \), then \( a=\ldots \ldots \ldots \ldots \ldots \) \( \begin{array}{llll}\text { (a) } 1 & \text { (b) zero } & \text { (c) } 2 & \text { (d) } 3\end{array} \)

Application 3: Simplifier les expressions suivantes: \( \begin{array}{ll}A=\ln (\sqrt{3})+\ln 3-\ln 9 & ; \\ C=\ln \left(\frac{1}{3}\right)+\ln \left(\frac{3}{5}\right)+\ln \left(\frac{5}{7}\right)+\ln \left(\frac{7}{9}\right) & ;\end{array} \quad D=\ln (\sqrt[3]{2}-\ln 16 \)

A solid is formed with triangular cross-sections where each triangle's base is defined by the equation \(y = x^2\) on interval \([0, 2]\). What is the volume of this solid?