Question

Como resolver esse sistema
2x-y=45
x+y=4

Answer 1

$\begin{cases}2x-y=45 \\x+y=4 \\\end{cases}\\\\\\2x+x+y-y=45+4\\3x=49\\\\x=\dfrac{49}{3}$

$x+y=4\\\\\dfrac{49}{3}+y=4\\\\\\49+3y=12\\3y=12-49\\3y=-37\\\\y=\dfrac{-37}{3}$

S={49/3 , -37/3}