Question

aflati numerele x si y stiind ca a) x - y = 10 si x/y egal 5/3
b)3x - y = 12 si x/y egal 3/5

Answer 1

Răspuns:

x-y=10 I·3

x/y=5/3=>3x=5y

3x-3y=30

5y-3y=30=>2y=30=>y=30:2=>y=15

x-15=10=>x=10+15=>x=25

_____________

3x-y=12 I·3

x/y=3/5=>3y=5x

9x-3y=36

9x-5x=36=>4x=36=>x=36:4=>x=9

3·9-y=12

y=27-12=>y=15

Answer 2

Răspuns:

a) x = 25

y = 15

b) x = 9

y = 15

Explicație pas cu pas:

a)

x - y = 10

x/y = 5/3 => x = 5y/3

inlocuim x

5y/3 - ³⁾y = ³⁾10

5y - 3y = 30

2y = 30

y = 15

inlocuim y

x = 10 + y

x = 10 + 15

x = 25

b)

3x - y = 12

x/y = 3/5 => x = 3y/5

inlocuim x

3(3y/5) - y = 12

9y/5 - ⁵⁾y = ⁵⁾12

9y - 5y = 60

4y = 60

y = 15

inlocuim y

3x = 12 + y

3x = 12 + 15

3x = 27

x = 9