Question

Usando o método da adição calcule o valor de x e y 2x+3y=5 -2x+8x=-16

Answer 1

$\left \{ {{2x+3y=5} \atop {-2x+8y=-16}} \right. \\ \\ cancela~~2x-2x=0~~e~~soma \\ \\ 3y+8y=5-16 \\11y=-11 \\ y=(-11)\div(11) \\\fbox{ y=-1 } \\ \\ substituir~y=-1~~em \\ \\ 2x+3y=5 \\ 2x+3(-1)=5 \\ 2x-3=5 \\ 2x=5+3 \\ 2x=8 \\ x=8\div2 \\\fbox{ x=4 } \\ \\ S=\{(4,-1)\}$