Question

Determinati numerele x,y si z stiind ca sunt direct proportionale cu 2,5si7 si x+5y+7z=760

Answer 1

Răspuns:

x/2 =y/5=z/7 =k

x/2 =k ;           x=2k

y/5=k ;           y=5k

x/7=k ;             z=7k

x +5y + 7z =760

2k+5*5k+7*7k =760

2k+25k+49k=760

76k=760

k=10

x=2k =2*10 =20

y=5*10 =50

z=7*10 =70

Explicație pas cu pas:

Answer 2

{ x ; y ; z } d.p { 2 ; 5 ; 7 }

x + 5 y + 7 z = 760

x / 2 = y / 5 = z / 7 = k

x / 2 = k => x = 2 k

y / 5 = k => y = 5 k

z / 7 = k => z = 7 k

2 k + 5 × 5 k + 7 × 7 k = 760

2 k + 25 k + 49 k = 760

76 k = 760 | : 76

k = 10

x = 2 × 10 = 20

y = 5 × 10 = 50

z = 7 × 10 = 70