Question

Resolva os sistemas de equações usando o método da substituição:

A) x+y=360
x-y= 140

Answer 1

$\left \{ {{x+y=360~(I)} \atop {x-y=140~(II)}} \right. \\\\\\\\ (I)~x+y=360\to x=-y+360\\\\\\ Substitua~(I)~em~(II):\\\\\\ x-y=140\to -y+360-y=140\to -y-y=140-360\to \\\\-2y=-220(-1)\to 2y=220\to y= \frac{220}{2} \to y=110\\\\\\ Agora~substitua~(II)~em~(I):\\\\\\ x=-y+360\to x=-110+360\to x=250\\\\\\\\ S=\{250;110\}$