Question

X+y=1 x-y=3 pelo método de substituição

Answer 1

$\large\left\{\begin{matrix} x+y=1&(1) \\ x-y=3&(2) \end{matrix}\right.\\\\\\x+y=1\\\\x=1-y$


$\text{Substitua esse valor de x na segunda equa\c{c}\~ao:}\\\\(2)~~x-y=3\\\\1-y-y=3\\\\1-2y=3\\\\-2y=2\\\\y= \dfrac{2}{-2}\\\\\fbox{ y=-1 }\\\\\\\text{Substitua o valor de y na primeira equa\c{c}\~ao para descobrir}\\\text{o valor de x:}\\\\(1)~~x+y=1\\\\x+(-1)=1\\\\x-1=1\\\\\fbox{ x=2 }\\\\\\\text{Solu\c{c}\~ao:}~~\large\left\{\begin{matrix} x=2& \\ ~~y=-1& \end{matrix}\right.$


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