Question

Repede vă rog repedeeee​

Answer 1

Explicație pas cu pas:

$\dfrac{x}{y} = \dfrac{7}{9} \iff \dfrac{x}{7} = \dfrac{y}{9} = k \\ x = 7k \ ; \ y = 9k$

a)

$\dfrac{5x + 2y}{2x - y} = \dfrac{5 \cdot 7k + 2 \cdot 9k}{2 \cdot 7k - 9k} = \\ = \dfrac{35k + 18k}{14k - 9k} = \dfrac{53k}{5k} = \dfrac{53}{5}$

d)

$\dfrac{18x - 14y + 25}{12 + 9x - 7y} = \dfrac{18 \cdot 7k - 14 \cdot 9k + 25}{12 + 9 \cdot 7k - 7 \cdot 9k} = \\ = \dfrac{126k - 126k + 25}{12 + 63k - 63k} = \dfrac{25}{12}$

(restul se rezolvă la fel... succes!)