Question

observe o sistema de equaçoes a seguir.

[ 3x + y = 20]
[ x - 36 = 2y ]

Answer 1

Sistemas:

$\mathtt{x - 36 = 2y} \\ \mathtt{x = 2y +36} \\ \\ \mathtt{Substituir~x} \\ \\ \mathtt{3x + y =20} \\ \mathtt{3~.~(2y +36) + y = 20} \\ \mathtt{6y +108 + y = 20 } \\ \mathtt{6y + y = 20 - 108} \\ \mathtt{7y = -88 } \\ \mathtt{y = -88/7} \\ \\ \mathtt{substituir~y} \\ \\ \mathtt{3x+y = 20} \\ \mathtt{3x -88/7 =20~~~~(7)} \\ \mathtt{21x -616/7 = 140 } \\ \mathtt{21x - 88 = 140} \\ \mathtt{21x = 140 + 88} \\ \mathtt{21x =228 } \\ \mathtt{x = 228/21~~(\div3)} \\ \mathtt{x = 76/7}$

$\boxed{\boxed{\mathtt{Resposta: x = 76/7~~~~e~~~~y = -88/7}}}$