Question

determinati numerele x si y stiind ca sunt invers proportionale cu 2 si 5 iar suma lor este 7

Answer 1

x/2=y/5
5x=2y
x+y=7
x=7-y
35-5y=2y
35y=7y
y=5
x=7-5=2

Answer 2

{ X, Y } i.p { 2, 5 }
X x 2 = Y x 5 = k
X x 2 = k ⇒ X = k/2
Y x 5 = k ⇒ Y = k/5
X + Y = 7
5)     2)
k/2 + k/5 = 7
5k/10 + 2k/10 = 7
7k/10 = 7
7k = 70
k = 10
x = 10/2 = 5
y = 10/5 = 2