Question

DETERMINE O PAR ORDENADO QUE SATISFAÇA O SISTEMA:{4X-Y=-12 E 5X-3Y=19 em seguida; calcule 6x + y COMO RESOLVER?

Answer 1

$4x-y=-12~equacao~I\\ \\ -y=-12-4x~.(-1)\\ \\ y=12+4x\\ \\ substitua~(y=12+4x)~na~equacao~II\\ \\ equacao~II\\ \\ 5x-3y=19\\ \\ 5x-3(12+4x)=19\\ \\ 5x-36-12x=19\\ \\ -7x=19+36\\ \\ 7x=-55\\ \\ x=-\frac{55}{7} \\ \\ substitua~(x=-\frac{55}{7} )~na~equacao~I\\ \\ 4x-y=-12\\ \\ 4.(-\frac{55}{7} )-y=-12\\ \\ -\frac{220}{7} -y=-12\\ \\ -y=-12+\frac{220}{7} .(-1)\\ \\ y=12-\frac{220}{7} \\ \\ mmc=7\\ \\ y=\frac{84-220}{7} =-\frac{136}{7} \\ \\ S=(-\frac{55}{7} ;~-\frac{136}{7} )$

$Calcule:\\ \\ 6x+y=\\\\6(-\frac{55}{7} )+(-\frac{136}{7} )=\\\\-\frac{330}{7} -\frac{136}{7} =\\\\\frac{-330-136}{7} =\\\\-\frac{466}{7}$