Question

am nevoie urgent pt maine​

Answer 1

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Answer 2

• metoda 1:

rescriem fracția și utilizăm coeficientul de proporționalitate k:

$\dfrac{x}{y} = \dfrac{2}{7} \Rightarrow \dfrac{x}{2} = \dfrac{y}{7} = k$

$x = 2k; \ y = 7k$

calculăm:

$\dfrac{x}{x + y} = \dfrac{2k}{2k + 7k} = \dfrac{2k}{9k} = \dfrac{2}{9}$

$\dfrac{2x + 3y}{x} = \dfrac{2 \cdot 2k + 3 \cdot 7k}{2k} = \dfrac{25k}{2k} = \dfrac{25}{2}$

• metoda 2:

calcul prin rapoarte derivate:

$\dfrac{x}{y} = \dfrac{2}{7} \Rightarrow \dfrac{x}{x + y} = \dfrac{2}{2 + 7} \Rightarrow \dfrac{x}{x + y} = \dfrac{2}{9}$

$\dfrac{x}{y} = \dfrac{2}{7} \Rightarrow \dfrac{y}{x} = \dfrac{7}{2} \implies$

$\dfrac{2x + 3y}{x} = \dfrac{2x}{x} + \dfrac{3y}{x} = 2 + 3 \cdot \dfrac{y}{x} = 2 + 3 \cdot \dfrac{7}{2} = \dfrac{4 + 21}{2} = \bf \dfrac{25}{2}$