Question

Determine X em cada uma das seguintes proporções

Answer 1

a)

$\dfrac{7}{3}=\dfrac{x}{12}\\\\3x=7\cdot12\\\\x=\dfrac{84}{3}\\\\\boxed{\boxed{x=28}}$

b)

$\dfrac{2x}{15}=\dfrac{6}{9}\\\\9\cdot2x=15\cdot6\\\\18x=90\\\\x=\dfrac{90}{18}\\\\\boxed{\boxed{x=5}}$

c)

$\dfrac{2}{9}=\dfrac{x+3}{x-1}\\\\2(x-1)=9(x+3)\\\\2x-2=9x+27\\\\9x-2x=-2-27\\\\7x=-29\\\\\boxed{\boxed{x=\dfrac{-29}{7}}}$

d)

$\dfrac{\sqrt{5}}{2}=\dfrac{x}{\sqrt{20}}\\\\2x=\sqrt{5}\cdot\sqrt{20}\\\\2x=\sqrt{2\cdot50}\\\\2x=\sqrt{100}\\\\2x=10\\\\x=\dfrac{10}{2}\\\\\boxed{\boxed{x=5}}$

Espero ter ajudado :)