Question

x+y=6 e 2x-y=24 pfv tem qe ser rapido ?

Answer 1

x+y=6
x = 6-y

2x-y=24
2(6-y)-y=24
12-2y-y=24
12-3y=24
-3y = 24 - 12
y= 12/3
- y = 4
y=-4

x=6-y
x= 6-(-4)
x = 10

Answer 2

$\left \{ {{x+y=6~(I)} \atop {2x-y=24~(II)}} \right. \\\\\\\\ (I)~x+y=6\to x=-y+6\\\\\\ Substitua~(I)~em(II):\\\\\\ (II)~2x-y=24\to 2(-y+6)-y=24\to -2y+12-y=24\to \\\\-2y-y=24-12\to -3y=12~(-1)\to 3y=-12\to y=- \frac{12}{3} \to \\\\ \boxed{y=-4}\\\\\\ Agora~substitua~(II)~em~(I):\\\\\\(I)~x=-y+6\to x=-(-4)+6\to x=4+6\to \boxed{x=10}\\\\\\\\ \boxed{\boxed{S=\{10;-4\}}}$



$Verificando:\\\\ \left \{ {{x+y=6} \atop {2x-y=24}} \right. \to \left \{ {{10+(-4)=6} \atop {2.10-(-4)=24}} \right. \to \left \{ {{10-4=6} \atop {20+4=24}} \right. \to \boxed{\left \{ {{6=6} \atop {24=24}} \right.}$