exercice 1 svp pour demain

1)
[tex]A = \frac{6}{5} - \frac{17}{14} ÷ \frac{5}{7} [/tex]
[tex]A = \frac{6}{5} - \frac{17}{14} * \frac{7}{5} [/tex]
[tex]A = \frac{6}{5} - \frac{119}{70} [/tex]
[tex]A = \frac{6*14}{5*14} - \frac{119}{70} [/tex]
[tex]A = \frac{84}{70} - \frac{119}{70} [/tex]
[tex]A = - \frac{35}{70} = - \frac{5}{14} [/tex]

2)
[tex]B = \frac{8*10^{8}*1.6 }{0.4*10^{-3} } [/tex]
[tex]B = \frac{1.28*10^{1} *10^{8} }{4*10^{-3} } [/tex]
[tex]B = \frac{1.28*10^{9} }{4*10^{-4} } [/tex]
[tex]B = 3.2 * 10^{12} [/tex]

3)
[tex]C = ( \sqrt{5} + \sqrt{10} )^{2} - 10 \sqrt{2} [/tex]
[tex]C = \sqrt{5}^{2} + 2* \sqrt{5*10} + \sqrt{10}^{2} - 10 \sqrt{2} [/tex]
[tex]C = 5 + 2 \sqrt{50} + 10 - 10 \sqrt{2} [/tex]
[tex]C = 15 + 2 \sqrt{25*2} - 10 \sqrt{2} [/tex]
[tex]C = 15 + 2*5 \sqrt{2} - 10 \sqrt{2} [/tex]
[tex]C = 15 + 10 \sqrt{2} - 10 \sqrt{2} [/tex]  ⇒ Les deux s'annulent
[tex]C = 15[/tex]