3. Giả sử trong nguyên tử Hyđro, electron chuyển động đều quanh hạt nhân theo đường tròn bán kinhh \( 0,53 \cdot 10^{-10} \mathrm{~m} \). Gia tốc hướng tâm là: A. \( 5,13 \cdot 10^{12} \mathrm{~m} / \mathrm{s}^{2} \) B. \( 5,13 \cdot 10^{22} \mathrm{~m} / \mathrm{s}^{2} \) C. \( 9,10 \cdot 10^{12} \mathrm{~m} / \mathrm{s}^{2} \) D. \( 9,01 \cdot 10^{22} \mathrm{~m} / \mathrm{s}^{2} \)

\( 2 \int \sqrt { 1 - e ^ { - x } } \cdot e ^ { - x } d x = 2 \int ( 1 - e ^ { - x } ) ^ { \frac { 1 } { 2 } } \cdot e ^ { - x } d x \)

1. Majorer et minorer sur \( [0,+\infty[ \) la fonction \( x \mapsto \frac{1}{1+\sqrt{x}}-2 \). 2. Majorer et minorer sur \( \mathbb{R} \) la fonction \( x \mapsto \frac{1}{1+(2+x)^{2}}+1 \). 3. Majorer et minorer sur \( \mathbb{R} \) la fonction \( x \mapsto \frac{2}{1+\frac{1}{2+x^{2}}} \).

1. \( y=x^{3}+x^{2}-12 x \) 2. \( y=(x-2)(x-1)(x+3) \) 3. \( y=2 x^{4}+8 x^{3}+4 x^{2}-8 x-6 \) 5. \( y=x^{5}+10 x^{3}-9 x \)

3. \( \left(2 a^{2}+a^{3}-2 a^{2}+a-2\right)+\left(12 a^{3}-a^{3}+2 a^{2}-5 a-1\right) a \) a. \( 12 a^{3}+2 a^{4}+2 a^{2}-4 a-3 \) b. \( 12 a^{3}+2 a^{4}-6 a+3 \quad 2 a^{4}+a^{3}-2 a^{2}+a=2 \) c. \( 12 a^{3}+2 a^{4}-2 a^{3}+3+3 \) d. \( 12 a^{5}+2 a^{4}-4 a-3 \quad \frac{18 a-a^{2}+2 a^{2}-5 a+1}{12 a+2 a^{4}} \)

The passage says people visit Cat island because A they art looking for jobs on fishing boats. B they want to see the cats. C they want to see their tarnilies.