Respostas

2014-05-24T15:15:37-03:00
 \left \{ {{5x+3y=50} \atop {8x+5y=81}} \right.

 \left \{ {{5x=50-3y} \atop {8x+5y=81}} \right.  \left \{ {{x= \frac{50-3y}{5} } \atop {8( \frac{50-3y}{5}) +5y=81}} \right.

 \left \{ {{x= \frac{50-3y}{5} } \atop {( \frac{400-24y}{5}) +5y=81}} \right.

 \left \{ {{x= \frac{50-3y}{5} } \atop 80-{ \frac{24y}{5} +5y=81}} \right.  m.m.c

 \left \{ {{x= \frac{50-3y}{5} } \atop 80-{ \frac{24y}{5} + \frac{25y}{5} =81}} \right.

 \left \{ {{x= \frac{50-3y}{5} } \atop 80+ \frac{y}{5}  =81}} \right.

 \left \{ {{x= \frac{50-3y}{5} } \atop \frac{y}{5}  =81-80}} \right.

 \left \{ {{x= \frac{50-3y}{5} } \atop y  =(81-80).5}} \right.

 \left \{ {{x= \frac{50-{3.5} }{5} } \atop y  = 5 \right.

 \left \{ {{x=7} \atop {y=5}} \right.

Substituindo os valores no sistema teremos
 \left \{ {{5x+3y=50} \atop {8x+5y=81}} \right. = \left \{ {{5.7+3.5=50} \atop {8.7+5.5=81}} \right.  \left \{ {{50=50} \atop {81=81}} \right.