Question

Sa se determine numerele naturale x,y,z direct proportionale cu numerele 2,5,8 si 2x+4y+7z=1988.

Answer 1

{x,y,z} d.p. {2,5,8} = k
x=2k
y=5k
z=8k

2x+4y+7z=1988 => 2 x 2k + 4 x 5k + 7 x 8k = 1988 => 80k= 1988/ : 80 => k =24,85
 x= 2k = 2 x 24, 7 =49,7
y=124,25
z=198,8

Answer 2

supra notez /
x/2=y/5=z/8=k
x/2=k⇒x=2k
y/5=k⇒y=5k
z/8=k⇒z=8k
2x+4y+7z=1988
2×2k+4×5k+7×8k=1988
4k+20k+56k=1988
80k=1988
k=1988:80
k=24,85
si calculezi x, y,  z
x=2k⇒2×24,85=49,7
y=5k⇒5×24,85=124,25
z=8k⇒8×24,85=198,8
apoi inlocuiesti in calcul