What was a negative consequence of the Industrial Revolution? A. Stock market instability B. Overcrowding of cities C. Poor quality crops D. Lack of needed workers

c. \( 15 \div 6=2 \frac{1}{2} \)

\begin{tabular}{|c|}\hline Peter and his friends ordered 10 pizzas. \\ They had \( 21 / 3 \) left. How much did they \\ eat? \end{tabular}

na temperatura de \( 20^{\circ} \mathrm{F} \) equivale a \( 68^{\circ} \mathrm{C} \), y \( 0^{\circ} \mathrm{F} \) equivalen a \( 86^{\circ} \mathrm{C} \). eratura en grados \( { }^{\circ} \mathrm{F}(x) \) con la temperatura y grados \( { }^{\circ} \mathrm{C}(y) \) \( y=\frac{5}{9} x+\frac{520}{9} \) \( y=\frac{5}{9} x+\frac{160}{9} \) \( y=\frac{5}{9} x-\frac{520}{9} \) \( y=\frac{5}{9} x-\frac{160}{9} \) encuentra la temperatura \( y \) en \( { }^{\circ} \mathrm{C} \) que cor- esponden a \( 23{ }^{\circ} \mathrm{F} \). \( y=-4^{\circ} \mathrm{C} \) \( y=-6^{\circ} \mathrm{C} \) \( y=-7^{\circ} \mathrm{C} \) \( y=-5^{\circ} \mathrm{C} \)

10. \( 4 \cdot 3^{4}+6 \)

Exercice 2: (1) Montrer les implications suivantes: a \( (\forall \mathrm{x}, \mathrm{y} \in \mathbb{R}) ; \quad \mathrm{Si} \quad(|\mathrm{x}| \leq 1 \) et \( |\mathrm{y}| \leq 1) \quad \) alors \( \sqrt{1-\mathrm{x}^{2}}+\sqrt{1-\mathrm{y}^{2}} \leq 2 \sqrt{1-\left(\frac{\mathrm{x}+\mathrm{y}}{2}\right)^{2}} \) \( \mathrm{~b}\left(\forall \mathrm{x}, \mathrm{y} \in \mathbb{R}^{*}\right) ; \quad 2 \mathrm{x}+4 \mathrm{y}=1 \Rightarrow \frac{1}{\mathrm{x}^{2}+\mathrm{y}^{2}} \leq 20 \) (2) En utilisant "Le raisonnement par les équivalences successives", montrer que: a \( \left(\forall \mathrm{x}, \mathrm{y} \in \mathbb{R}^{+}\right) ; \quad \mathrm{x} \sqrt{\mathrm{x}^{2}+1}=\mathrm{y} \sqrt{\mathrm{y}^{2}+1} \Longleftrightarrow \mathrm{x}=\mathrm{y} \) \( \mathrm{b}\left(\forall \mathrm{x}, \mathrm{y} \in \mathbb{R}_{+}^{*}\right) ; \quad \mathrm{x} \prec \mathrm{y} \quad \Longleftrightarrow \quad \frac{\mathrm{x}}{\mathrm{y}} \prec \frac{2 \mathrm{x}+5 \mathrm{y}}{5 \mathrm{x}+2 \mathrm{y}} \prec \frac{\mathrm{y}}{\mathrm{x}} \)