Question

Con resolución plissssss​

Answer 1

Se tiene la proporcion

$\frac{a^{2} }{8} =\frac{b^2}{50} =\frac{c^2}{98}=\frac{d^2}{200}=k$

Sacamos radical a todos

$\frac{a }{2\sqrt{2} } =\frac{b}{5\sqrt{2} } =\frac{c}{7\sqrt{2} }=\frac{d}{10\sqrt{2} }=\sqrt{k}$

Sumamos las proporciones y lo igualamos a la  constante

$\frac{a+b+c+d}{24\sqrt{2} } =\sqrt{k} \\\\\frac{240}{24\sqrt{2} }=\sqrt{k} } \\\\\frac{10}{\sqrt{2} } =\sqrt{k} \\\\5\sqrt{2} =\sqrt{k}$

Calculamos

$d-c+b-a\\\\10\sqrt{2}(\sqrt{k}) -7\sqrt{2}(\sqrt{k}) +5\sqrt{2}(\sqrt{k}) -2\sqrt{2} (\sqrt{k}) \\\\6\sqrt{2} (\sqrt{k}) \\\\6\sqrt{2} (5\sqrt{2} )\\\\ 30(2)\\\\60$

Respuesta A