Bonjour
Mzlle03
[tex]1)\ A=\dfrac{5}{7}+\dfrac{8}{7}\times(-\dfrac{6}{49})\\\\\\A=\dfrac{5}{7}-\dfrac{8\times6}{7\times49}\\\\\\\\A=\dfrac{5\times49}{7\times49}-\dfrac{8\times6}{7\times49}\\\\\\A=\dfrac{245}{343}-\dfrac{48}{343}\\\\\\\\A=\dfrac{197}{343}\\\\\\\boxed{A=\dfrac{197}{343}}[/tex]
[tex]2)\ B=\dfrac{4\times10^4\times13\times10^{-7}}{9\times(10^2)^6}\\\\\\B=\dfrac{4\times13}{9}\times\dfrac{10^4\times10^{-7}}{(10^2)^6}\\\\\\B=\dfrac{52}{9}\times\dfrac{10^{4-7}}{10^{2\times6}}\\\\\\B=\dfrac{52}{9}\times\dfrac{10^{-3}}{10^{12}}\\\\\\B=\dfrac{52}{9}\times10^{-3-12}\\\\\\\boxed{B\approx5,8\times10^{-15}}[/tex]
