Răspuns:
Explicație pas cu pas:
c) 7 / x = 3 / y = k (coeficient de proportionalitate)
=> x = 7 / k
y = 3 / k
5x - 4y = 69 => 35 / k - 12 / k = 69 => 23 / k = 69 => k = 1 / 3
=> x = 21
y = 9
d) 1 / x = 2 / y = k
=> x = 1 / k
y = 2 / k
x^2 + y^2 = 45
1 / k^2 + 4 / k^2 = 45 => 5 / k^2 = 45 => k ^2 = 1 / 9 => k = 1 / 3
=> x = 3
y = 6
