Question

Resolva os sistemas de equaçoes pelo metodo da substituiçao (exercicio 7 )

Answer 1

$a\left \{ {{x=8} \atop {x+y=17}} \right. \\\\\\\left \{ {{8+y=17}\right.\\ \\\left \{ {{y=17-8}\right. \\\\y=9</p> <p>b\left \{ x=2y+2} \atop {x+y=8}} \right. \\\\\left \{ {{2y+2+y=8} \right. \\\\\left \{ {{3y=6} \right. \\\\\left \{ {{y=}\frac{6}{3}  \right. \\y=2$ $</p> <p>c\left \{ {{x+2y=7} \atop {4x-y=10}} \right. \\\\\left \{ {{-4x-8y=-28} \atop {4x-y=10}} \right. \\\\\left \{ {{-9y=-18} \right. \\\\y=\frac{-18}{-9}  \\y=2\\\\x+2.2=7\\x+4=7\\x=3$$</p> <p>d\left \{ {{5x-y=4 .(-1)} \atop {2x-y=-5}} \right. \\\\\left \{ {{-5x+y=-4} \atop {2x-y=-5}} \right. \\\\-3x=-9\\x=\frac{-9}{-3} \\x=3\\\\2.3-y=-5\\6-y=-5\\-y=-11\\y=\frac{-11}{-1} \\y=11$